Consider going to Pattaya for 1 night - just to see it, to learn. This is not your only trip to Thailand. You will get the bug and be back soon. This is your trial trip.
You can double up on a hotel - it is only a bit of money. No need to check out. Morning taxi to Pattaya (2 hr ish), in hotel for noon. GC all day, Soi 6 in early evening, Walking Street late, crash in the one night hotel. Next day wake up next to a girl-that-you-don't-remember-hiring. Fuck her, then send her away. Breakfast. Look, there is the beach. More GC in afternoon. Then taxi back to BKK.
External Link/Members OnlyThen for next trip you'll have a better idea of options.
Your call but high end agencies? Those are for Dubai and London. In Thailand, just tour around till you spot the look you want. When in Rome, do as the Romans do.