Welcome to our forum.
I am married but my wife has told me to get whatever works for me best. She is normal sized... lol, so she figures that my tallness factor should be the most important consideration (bless her!). If I narrowed it down to a couple I would certainly solicit her feedback.As to the Aria, I saw one of those but it looked pretty small overall. Interesting observation about the foot jets. It is indeed my left ankle. The guy at the Hot Spring store seemed pretty convinced that I was too big for that one. But I only sat in it dry and my recollection is vague. Looking at it now both it and the Envoy look like really nice configurations for just two people. If only I weren't so damn tall! (and long torso'd!)
Do yourself a favor and check out the Bullfrog A8 or R8. Little history, I lost a sale to HS about 10 years ago to this guy that's 6'7". He bought a Grandee over a Jacuzzi and had nothing but trouble with it over the years. The current BF was not available at that time. I am not dissing Hot Springs, it's what fit him the best at that time do to his height. He stuck out of the Jacuzzi like a sore thumb! He is a local business owner and money is not an object, and so he went with it. Fast forward to today, he built a new house this year and left the HS behind with it's woes. He and his wife came in today and wet tested a Bullfrog A8 he fit well in it and so did his 5'6 wife. They may even go down to the R7 which he fit in fine as well. They do not need the size of the A8, kids are gone and it's just he and the wife. Give it a shot and see what you think. Hopefully the dealer can get his tub not to smell moldy. I have no horse in this race, but you should try the Bullfrog out and see what you think.
"Dry" testing, the Grandee looks like the water line would be the highest. Perhaps I shouldn't make that the end all/be all of my decision but it seems important. I wet tested a Vanguard and it felt like a really nice high quality product. The Marquis I tested was also nice but it was a smaller model and felt cramped. I loved the foot jet in it, though. The local Bullfrog dealer seems sub-par and they have almost nothing going on for lower body jets, but if they could manage to get a tub full that didn't smell moldy I'd give it a whirl (no pun intended!). I haven't seen the Maxx yet, and they recently bough L.A. Spas, but even though the dealer seems really nice I wasn't impressed with the quality and they didn't seem much less expensive then the premium brands.
The overall height of the spa doesn't necessarily tell you it's going to be deeper than another spa with similar or less height. For example, the 38" tall Grandee has plumbing underneath the footwell for the drain, so that spa is going to have at least 1-2" less water depth than a spa that doesn't run plumbing underneath the footwell (for instance the Epic).