To be honest, Khao San is a bit of a scar on the city but it's well and truly here to stay, my advice is to enjoy the nightlife but stay away from the elephants etc, it's just plain cruel. We have had a couple of great nights so far, Thailand is definately a good place to meet other travellers easily, it was much harder in Vietnam.
Thai food blows all other we've had so far out of the water. The roadside kitchens serve the best curries and Pad Thai on the market and at a fraction of the price. Provided you pick a busy, clean kitchen, there's no reason not to eat there, you'd be mad to pay more (plus there's a great buzz around these places).
There's plenty of sightseeing to be done in Bangkok but so far we've been so involved in the Khao San scene (the perfect antidote for visitors fresh out of Vietnam/Cambodia) that we've only had chance to visit the Grand Palace.
Outside you'll encounter the same old scams, "it's closed between one and four, for prayer" etc, just ignore them, you'll end up at a dodgy tailor or worse, a gogo bar. Inside it sparkles, the pillars are decorated elaborately with gemstones, it looks like it was designed by Liberace. It's not tacky at all though, in fact, it is far more breathtaking than the palace in Pnomh Penh, if a little more expensive.
Around every corner there's images of Buddha, which you must respect by never pointing your feet towards, it's a beautiful place. In fact, the only blotch on the landscape that day was me; you have to wear long trousers and no flip-flops etc, all i've got in the backpack is my jeans and boy did I sweat, I glistened in the sun more than the palace did, honest.
So far so good, better actually .......
Most visitors to Bangkok will head straight for Khao San Road, it's plain mad. By day the street is lined with vendors selling the best knock-offs you'll find and they're not expensive at all. By night it's lined with dodgy makeshift bars displaying signs such as "Cheap drink, very strong, we no check ID", scores of street sellers flogging the worst souvenirs imaginable and the occasional elephant plods on by.