As for a mid-range hotel very close to the airport you may want to check-out
Hotel Novotel Suvarnabhumi Airport: book your Novotel hotel in BANGKOK. I have no clue what they have to offer other than normal accommodations, however, at the old airport there were some FL activity in the airport hotels as well as massage services. Look at the hotel sites for a phone number and call the hotel concierge or guest services and ask them what you are looking for.