Why the fuck would anyone want to fly 6,000 miles to spend time down Khao San Road with the great unwashed?? FUCK THAT. Full of wannabee hippies with a guitar with three fucking strings on it, talking about how little they have spent over their three-six month holiday. Wankers. I fucking despise these parasites.
Bangkok is ok for 3 nights max, do the touristy thing, temples etc, then night times, Patpong, Soi Cowboy and Nana Plaza (make sure to pop into Hot Lips go-go on the first floor at Nana Plaza, manager is a Blue).
If you want drunken debauchery/stories to tell when getting home then Pattaya for a few nights is a must, soi 6 daytime and Walking Street/many other areas at night.
Krabi is the most beautiful place I have visited out there, Phuket is ok, the beach at Kata Noi is nice, and a ferry ride away is Phi Phi island, again, stunning scenery.
Just remember the golden rule, never have a girlfriend with a bigger cock than you.