View this post on Hive: I got a new sauna!
I would get the last one - with that, you can alternate (between full body and feet) with your partner too.
That last one is kind of funny looking, but I realize it's a promotional shot. That said, it's probably the most versatile from a utility standpoint.
At our previous house, we created a built-in by converting a closet. The insulation and wood was not cheap but it sure was nice to have. The most expensive part was actually the electrician who put in a new wire run to the fuse box, because they draw so much power.