There are spas and massage available at the airport. If you're looking for something other than a traditional or foot massage, you'll have to leave the airport. There's some massage parlours about 15 minutes away right off Rama IX Rd. not far from the airport.
http://www.suvarnabhumiairport.com/ebiz/NBIA.portal?_nfpb=true&_pageLabel=NBIA_page_FacilitiesServices