Unless you want the extra luxury, Premier are rarely competitive with TL. Particularly for flexible bookings, where Premier really load the rates.
Accor is a brand worth considering, particularly their budget Ibis brands, and they offer members and early-booking discounts. Again, their calendar function allows you to easily scroll through dates to see the prices. They used to have a members sale each week to offload unsold rooms for the following week, and I got some incredible deals, but unfortunately they stopped it. I can remember the receptionist at one Novotel saying that even staff couldn't get that rate!
One thing to watch out for is that many hotels seem to base their pricing on anticipated demand. If bookings don't come in at the rate expected, the price will drop. Pricing these days is very dynamic, and the rate for staying on a particular day can vary dramatically, up and down, from day to day. If you see a bargain, grab it there and then. I have a suspicion that prices also vary depending on the time of day you look, rising during the working day when businesses are booking, and falling in the evening.