Best US Hotel Affiiate Program?

I am making some US city portals which I'd like to monetize using hotel and airlines affiliate programs.

Can anybody suggest good hotel affiliate programs for US cities - which have a good selection of hotels, offer co-branded sites or features easy to integrate, are transparent in dealings and pay regularly.

Thanks in advance for your suggestions.

Try booking.com

i've done priceline and they pay nicely. don't know if that's what you want though

Thanks. Booking.com is a partner site of priceline.com - so is it better to go for priceline?