Hi Norrad,
I think that there is no real need to book in advance for Bangkok. You might try a night at the Nana Hotel and, if that does not suit, you can have a look around during the day.
nanabkk@nanahotel.co.th ; I e-mail them for a room for as long as I am in Bangkok and then take it from there.
If you aare looking a bit more upmarket there are loads of top-end hotels around, maybe the Bayoke Sky?
Enjoy
