You are correct, there are many choices for spas, and the prices can vary a lot. I solved the problem of deciding on which compnay to go with by going with what a life long friend recommended. After high school graduation he went to work for a small company then making spas, was called Cal Spa.
He lives in the Seattle area and his spa is the normal outdoor installation, had been using it for about 2 years and had one problem, one of the jets needed replacing.
We have had the Cal Spa in use for 24/7 and this is the sixth year of use, and the only thing I have needed to replace was the ozinator, which is normal, other than that, there has beenno repairs/maintainance by a spa tech.
If you want a powerful spa, the best way to accomplish that is by going with two powerful pumps, and the most jets that are available. I upgraded this model to two 5hp GE motors, and a total of 56 jets, and all of the options avaialble at the time, except the music system. The cost of the spa in 2000 was $10k, which was not cheap, but since it was going in a room that would make it very expenisve to ever remove it, or to make any changes later, went with what I thought would last. The electronics were covered for five years, the pumps for 10, and the finish on the tub for 25 years.
All of the pumpss/electrics are located in a packaged area, so with this design, you really only need access to one side of the spa. Making it good for an in house install where having access to all sides may not be possible.
Having a spa indoors is not what most people do, so there was no real expeerts to suggest how to do things, so I have learned a lot on my own and will give a few suggestions.
1) One needs a floor level permanet drain, and a fresh water supply line to the spa. Since the water level will change according to how many people are using the spa, one needs to remove and add water as needed. Also most spa companies do not recommend using treaded water, so if you have a treatment system for the house water, a seperate supply should be used for the spa.. Treated water seems to also casue the problem of adding a lot of foam to the spa, so anoter reason to use non-treated water.
2) The floor and walls surrounding the spa needs to be water resistant, if you have a powerful spa, when its running on high mode, all jets operational, it can and will spill over the top when you have several people in the spa. This is one of the reason I have tile on the floors, walls, water is never a concern.
3) All spa sales people inisist you need to use a lot of checmicals to keep the water balanced and clean. This gets to be a costly monthly expense, and also can be a pain to keep all in balance. Also they don't tell you that most the repair cost of a spa are created from the reaction of the chemicals on the equipment and jets. So for keeping the water clean and balanced, I have done as my friend recommended and elimminated all chemicals and only use brominating tablets. By doing this the water stays bacteria free and clean for about 3 to 4 months with the spa being used daily.
4) The spa filters are the clue to keeping water clean and maintainance down, I wash the filters out weekly, takes about 15 minutes, and also saves on the cost of replacing the filters. The two filters I have now are sereral years old and are like new, again, you will be told they need to be replaced yearly. You can by which ever filters and chemicals you use online, much more cost effective than a local pool/spa shop. I use a spa gloss on the tub, apply it twice a year, and after 5 years, the tub looks like it did the day it was delivered.
As normal, this is just my opinion and I'm just a happy customer of Cal Spa, good luck on the decision making.
Cal Spa