Budget wise Its the Ibis or Everich Inn,
Good value bit more baht. DIG, Dariwn, Le Fenix or Grand Buisness Inn.
Plenty more to choose from, personaly I do like to try a diffrent hotel each time I go.
Have you tried,
Darjelling Boutique Hotel
Address: 390/35-36 Sukhumvit Soi 18
Location: Sukhumvit
1200 a night
CT