Sorry taking a while to post but home circumstances mean it's not v often I can get on here.
Regarding the non-punting stuff most of the early posts from JRC hold true. Beer is much cheaper if you drink from street stalls, but it's still v expensive in Malaysia. The reason is that it's a majority-Muslim country so they take the view that's it's ok to tax the hell out of us infidels. In KL you should pay about RM13-17 for a large Tiger (£1 = ~RM4.8). If you drink only from the bars of 5 star hotels in London you'll get caned and KL is no different. There are pubs in KL but most of them are run by gangsters and I find them pretty featureless and occasionally hostile (but see exception later). I prefer to drink in a street stall, grab some food if I'm hungry and watch the world go by. Don't be squeamish about eating from street stalls, it's how Malaysians eat and you'll get some great food and experiences. Jalan Alor, which runs parallel to Bukit Bintang is a great area for stalls, food and drinking, they stay open till very late. Contradicting my earlier advice there are actually a some decent pubs near hear as well - on Changkat Bukit Bintang, which is just around the corner. Take care with your stuff around here, street crime is very bad - more later. Petaling Street (where you get the fake watches) has good food stalls but beware of touts. There's a lot of upmarket eateries around Bukit Bintang. Also nearby are a couple of interesting malls - Sungei Wang and Low Yat Plaza. The latter is all things tech but know your stuff and be prepared to bargain hard - start off with about 35-40% of the asking price and you should not pay much above half the original asking prices. Don't be afraid to walk if the price isn't to your liking, so long as you look as though you mean it then more often than not it soon will be(same applies to the ladies as well!! - see later). Some good deals to be had if you're a gadget boy but I'd avoid if you don't know your stuff, there's also a lot of scams and fakes.
A good 4 star hotel can be had around here for £40-£50 per night and will be near Bukit Bintang area. Use the train to get from the airport to centre of KL (KL Express, tickets cost RM35), and then a taxi to your hotel - you can go to a desk and get a pre-paid ticket. btw some airlines (inc. MAS and Emirates) allow you to check-in at the station on your return flight to the UK, which avoids you lugging your bag on the train. Taxis are meant to keep their meters on but this is enforced v haphazardly and your chances of getting a taxi to use the meter after midnight are slim and around Beach Club / B-Bintang, pretty well non-existent.
One point where I am going to disagree with JRC is on safety. Street crime, especially snatch-thieving, is rampant and out of control, and as a tourist you are a target. Common MO is 2 guys on a moped, one drives and the other snatches. They are more often than not armed with Parangs (machetes) which they won't hesitate to use if you resist and are frequently high as a kite. There have been cases of people killed or seriously injured because they didn't or couldn't let go when their bag was snatched and got dragged under traffic, and people killed or seriously injured when they've resisted and the parangs have come out. To redress the balance, several snatchers have been killed or injured when they've been caught and locals have taken the law into their own hands. Usual precautions apply - don't flash your stuff, wear a cheap watch, chains stay in the hotel safe, try to walk away from the edge of the pavement, keep your bag facing inwards, carry only the cash and other stuff that you need, have a spare credit card back in your hotel room and keep your senses about you - I'd avoid getting legless. Snatching occurs at all times of day, including in broad daylight on packed streets but is obviously worse at night. If you are a victim, don't resist - though the likelihood is that it will be over and done with before you even realise what's going on.
Bukit Bintang is incidentally a former RLD and you still get streetwalkers there, nearly all PRC's. I tried one once out of curiosity and paid RM150 - she was no looker but a marvellous shag, not something I'd repeat though. There's a lot of building work going on at the moment because the metro is being extended and new station built so expect pavements even more crowed and traffic even more chaotic than normal. You will also get hassled by touts offering girls on Bukit Bintang - I don't ever buy anything from a tout, whether it's a girl or anything else.
For the punting, JRC is right on the nail - you really don't need to go any further than The Beach Club and his description of what you'll find there is v accurate. Price wise, it's down to you, those girls will take as much as you want to give them, but for overnights you should pay about RM300 - 400. They'll generally start by asking RM800 or even more; if you've reached an impasse at RM500-600, don't be afraid to say no deal, and walk off. You'll be amazed how quickly the price comes down, so long as you look like you mean it. I always go for an overnight, (and I book my hotel as a couple!!), so I can't comment on prices for ST. There are a lot of LB's and other street walkers outside, never tried either. There's also 2 /3 other clubs directly opposite and some nearby bars that have hookers, but the choice and standard isn't as good as Beach Club. Watch out for the Viet girls - cunning little vixens, though damn pretty and usually v good. They will often try to take payment beforehand - and of course after a couple of hours of your "overnight", they will be ill, or their friend will be in trouble and they have to go, or....etc. And 20 minutes after whatever calamity befell them they'll be back in the Beach Club trying to get another fee for the night. It's not worth starting the hunt for overnights until midnight and always make sure before you leave the Beach Club that the lady understands and accepts that she's getting paid in the morning.
I've tried the massage parlour stuff and generally in my view is it's pretty good value. There's different types; along the streets of Bukit Bintang you will see numerous girls sitting on chairs holding cards offering massages. The format is the same - the girls are usually ok looking- but with the occasional old bat, who I've always avoided - but not stunners, and often in their 30's or 40's. You will get a proper massage by a girl who knows what she's doing at the rate shown on the card (but ask for a small discount) and part way though you'll be asked if you want a special. This should cost you about RM150. Whilst the format is the same the experience can be variable - again the girls will ask stupid money to start with and don't be afraid to say you just want a straight massage if the price doesn't seem to be coming down. I've had a couple of skanky HJ's but I've also had several that were brilliant. I had one regular PRC that I used to visit for about 3 years, but sadly she's been moved out by the construction works, and despite having her phone number I can't find her anymore. Depends on circumstances and personal taste but often a good proper massage finished off with a good HJ can be better than FS.
Finally there are Spa's. Some of them are standalone and some within hotels and generally my experience again is very positive. You will pay about RM198 (the price is always RMxx8 for some reason that I've never figured) for 45 minutes with the lady. Green Elephant, which I've been to a few times has mainly local Malaysian - if you do go there ask for Farah. E2 is popular but I've never been. Nova Hotel is my favourite, they have a selection of Thai, Indonesian, Vietnamese or PRC's. The girls are generally ok, and you should have 6/7 to choose from, which gives enough choice to avoid the occasional munter, and I've had 3/4 absolute crackers as well. Good option if you just get a random attack of desire in the trouser dept, or to finish off a hot and sweaty afternoon of shopping, or as a prelude to a night on the beer.
Do be aware about the crime but don't let that put you off - the Malaysians who aren't trying to mangle you with a parang (which is 99% of them) are a generally friendly - be friendly and open, mix in, eat the local food, speak to your hotel staff for tips about where the locals go, and you'll have a great time. And that's before you even set eyes on the ladies!!
Anyway I think that's enough from me and apologies for the length but I hope you find bits of this useful and I'm as jealous as hell.