Another geekgranny Book
Look for multiple pumps also. Mine has one main circulation pump and two jet pumps, one for each side of spa, and a separate one for the bubbles. The jet pumps work separately or together. It's especially nice if you want jets on your side and another doesn't want any. Ours has option to run circulation twice a day for the time we set or 24/7. Some people don't want or need circulation/filtering running 24/7 but with our high/frequent usage and extreme summer heat we run ours 24/7. With 220v I don't think the filtering circulation uses much electricity.
Ours has separate returns for ozone and main circulation. Of course the ozone return puts out bubbles but ours also puts out bubbles from the main circulation return. It's a wonderful indicator to me to change out the cartridge filter when the bubbles stop coming out of circulation return.
(we normally keep at least two good filters - I have four so that when it is time to do a long filter soak in a more thorough cleaning product I can get more use of the product). I usually change out/clean the filters no less than twice a week so having four is handy.
Another really important feature is being able to turn on the venturi for each area to bump up the jet action higher/stronger. Sometimes I need more jet pressure than our strong jets provide especially for my neck. I'm investigating changing around some jets or purchasing a couple to get even stronger action in my favorite seat. That's why I advise getting jets that you can change around yourself.
Our spa is an Aries, made locally. We've had this one for seven years (our first Aries but third spa). We went out to the factory and sat in every model they had (dry) to pick out the seats we wanted and then where we wanted the jets and what type of jets. Many of the jets can be changed out for other ones too. We had a lounge in previous spa and didn't use it much because human bodies float so it was impossible to get the jet action on neck and back without being pushed away from them.
One really important thing I would look for too is jets that will not become stuck; that is the ring around them to adjust pressure. When the spa guy was out here this spring I asked him how to keep ours freely moving. He said "use them", that is adjust them often to keep the sand, sediment, etc., from jamming them. He then suggested I get a small, pipe collar wrench to help free them up. I'm still working on them but the wrench helps.
Look for jets that are user interchangeable and ones that are least likely to have the adjusting collar jam from debris
BTW... keep the water balanced. I had the circulation pump replaced less than two years ago and had to get another replacement this spring. Less than 2 yr old pump started leaking from the shaft at some point, not enough to indicate a leak as we do have to account for some evaporation, especially as it is so hot here in summer that it takes days for the temps to fall much in summer if I turn heater off, with circulation pump going 24/7 and insulated cover on most of time and I use the spa for several hours, several times a week. (back, neck, shoulder therapy) The first thing he asked me when he looked at the pump condition was, "Are you keeping your water balanced at all times?" I told him "yes" (I was not telling the truth)

Bottom line, the pump warranty for first replacement was only one year and probably would not have failed if I had kept water in balance. BTW... the original pump lasted over five years AND it didn't "break". It had just started making some noise that indicated some bearings or something going out. And I didn't like hearing the noise. KEEP WATER BALANCED :!: :!:
Original bubbler motor went out after 7 years which I had him replace this spring. The original cover, also lasted 7 years but really needed replacing after 5 when a friend got up on it and broke the insulating foam. It is in full Texas sun most of the day.
Three years ago I added a cover rack. Get that for sure. I chose the one where you open cover then slide the folded cover on to racks that swing out from back side. We chose that because most of the others hold cover so view is blocked on that side. We want to see the woods and bird feeders when ours is open AND the one I purchased was the cheapest. I installed it myself in little time.
Another thing to get for sure is a safety rail for getting in and out of tub. We didn't have one until the spa guy came out this spring. I can't believe we didn't put one in sooner. Hubby is 74, gets around great, but not as agile as previous years. AND if you happen to let water get out of balance, but still looking clear, you are less likely to slip and fall on the slippery invisible bad slime.
Ask around a whole lot and see as many spas in action as you can. The Texas State Fair usually has a whole tent where spa reps have running spas. I figure that might be so a many State Fairs. The Home Shows, as suggested in another post, are another great place to compare and ask ask lots of questions and compare jets between makers.
Hope this helps someone considering purchase. geekgranny=alice