Gunite Spa Design
Closing the Comfort Gap in Spas - Aqua Magazine gives a good overview of what is possible.
Spa Seat Design
Its not uncommon to have angled back rests, foot supports and rolled bond beams. There really is no limit to what is possible.
Attached spas are 100% customizable. A spa was built for a very picky lady. She put on a tyvek suit and lay in the wet plaster in the spa so it was contoured to her body.
The bottom line is you can get whatever you ask and are willing to pay for.
Paramount ParaJets massage therapy spa jets allows the ability to change or move the therapy jet faceplates to different stations in your spa with a simple twist. ParaJets offer 4 interchangeable massage therapy jet faceplates; Deep Tissue, Shiatsu, Pulsating or Soft Stream.
Spa Air Bubbles
Some spas get air bubbles into the jets through a venturi system pulling air through an open pipe. Other spas use a powered Spa Air Blower for bubbles through the jets.
The Paramount Air- Port is a muffled air intake that can be installed in the deck near the spa. The Air-Port eliminates the need to run extended air intake lines and thereby eliminates the problems associated with flooded lines.