I can tell you that as crazy as it sounds, New York is a lot more conservative than London. It's harder to find working girls than you'd think. As a tourist, it's harder still.
Having said that, where there are men with money, their are girls willing to take it. The main info hub is Craigslist.org. A while back they made an effort to clean up but I did look on their recently and I see the girls returned to posting there.
It's not easy to spot massage places that do extras. If its open late, it's more likely. if they advertise using phrases such as 'release your stress' then it's more likely. If craigslist isn't doing it for you you can just walk around the chinatown area of downtown Manhattan. You can easily spot them and will usually be a walkup or a walk down to the basement premises. You may get extras or you may not. prices are typically $40 - 60$ per hour with $40 for a happy hand or mouth ending. Full sex is rarely an option.
If its more full service you want then you'll want to look for a korean massage place. I would google them. Prices run to about $200 all in. $40 to the house for the massage and the rest upfront for the extras. They typically have a door you ring with CCTV.
As a tourist getting an escort is harder than a massage. Again, casual encounters on craigslist will help you out. i've looked at Backpage.com for NY and I'd say this is not where the action is. Picking girls on Craigslist is going to be hit and miss - and you'll need a phone to pull that off. I'd stick to locations between the financial district thru downtown SoHo, Lower East side, and up teh Upper east and upper west side to about 100th street. Midtown is going to be a good area to stick to because thats where most tourists stay and they are used to dealing with them. I would avoid brooklyn, queens, and north of 100st street (harlem, bronx etc).
If I were you, i'd stick to a chinese massage and hope for the best.