Swim spas/exercise pools offer great benefits (as well as hot tubs/spas). We recommend L.A. Spas made in California, USA. They come in many varieties in regard to size, jets, seating arrangements, technology packages, water features, colors, etc! You can research more below.

You bring up an excellent point about access for servicing. In some cases where these products are recessed, there can be rooms built below for access to service.

Another thing to consider before recessing your hot tub/spa/swim spa/exercise pool is - how easy is it for you to actually get into the product from a standing position? Hot tubs/spas can be up to 40" deep and swim spas/exercise pools up to 53" deep. For some, that can be quite deep and an unsteady maneuver getting in from a standing position. So most of our clients choose to place their L.A. Spa product on top of proper decking, use steps up to the spa side, place their bottom on the side of the spa, swing their legs over the side and slide in. This placement ensures proper access area for servicing and a safer way of entering their spa.

Good luck!

http://www.houzz.com/ideabooks/13858227/thumbs/Swim-Spas
http://www.houzz.com/ideabooks/13498285/thumbs/Hot-Tubs---Spas---Premium-Collection
http://www.laspas.com/