For your trip i would recommend Dream hotel on Soi 15, i was there in september, paid about 65 USD a night. Amazing, GF, got bumped up to deluxe room, they'll make up your room at any time you want, so you can wake up at 5 pm and still have it done. Great pool, great restaurant, friendly, no hassling, they watch out for you.
And for location youre halfway between nana and cowboy, and insomnia is down the soi at suk. You cant go wrong here!