I love that you have decided you would rather be in a hot tub than on a vacation! I couldn't agree more. I use my spa 3- 4 X a week and my hubby is in it everyday. It is THE best way to relax, soothe my aching gardening muscles and just re-group.
So congrats on making a great decision.
Researching on line is the best way to figure out what manufacturer meets your needs. There are some great choices today and if you read the chats on this forum you will see them represented here. Visit the manufacturers sites as well.
Hot Springs, Sundance, Cal spas and Marquis have all been around for a long time and there is a lot of info. available on them all.
Visit at least 3 - 4 dealers before you leap! And please, don't fall for the 'gotta have these bells and whistles" over quality. In the long run efficiency, ease of maintenance, warranty, and quiet operation matter more than a fancy light or stereo! (IMO)
I also think it is really important to know your dealer is going to provide you with the expertise and service you deserve AFTER the sale. You can always call stores and ask them who services their spas or if parts are available on an older models...