i always recommend you read www.stickmanbangkok.com this will give you an insight of Thailands adult night life
Pattaya is probably the best location to go too if you are a solo sex traveler, it has modern hotels, new shopping centres, plenty of tourist attractions, but the good thing about the city you can walk everywhere, or get the Baht Bus, the best way to get to Pattaya from Bangkok airport is get the private Blue cabs, down stairs near the escalators at the end of the regular taxi line, never catch a regular cab, the cabbies are always peaking on red bulls, if you have the cash catch a limo, private car from upstairs

Hotel choices, you want to pick a hotel thats at least 4 stars, has an ocean view, guest friendly, a pool to chill out by, and free breakfast, as you are on holidays and you want a room thats comfortable, you also want to have breakfast for 2 included in the price just incase you get a girlfriend while you are staying there,

i find freelancers make the best GF, they are normally from Isan and they go to school/college or work during the day and look for Johns at night in the clubs, to have fun with and make extra cash, so they are with only one guy at a time,
beachgirls are just freelancers who's full time job is to stand at the beach and fuck as many short stayers as possible, than do long stays at night so they have a room to sleep in, not a good choice for a GF
BarGirls and GOGO girls, end up costing more money than they are worth, you will end up paying a daily bar fee, and a more expensive price than freelancers,
soapy Massage girls and fish bowl girls, are lots of fun, you at least got to try it, so you won't regret it, but not good for a GF experience,
pattaya is also full of russian girls, most of them are very beautiful and you got to at least try them,
while you are there always keep in mind everyone is trying to rob or scam you, so always lock up your valuables and only carry enough spending cash for the day