I have a small above ground pool, and a hot tub and folks ask me which I like better.
I usually answer the Hot tub. I'm in MA and use the tub all year round (although yes, in July and August, it's not much. Maybe once a week). But in the cooler months...forget it. It's the best. I absolutely love being able to go outside at night, in the middle of Febuary, crack a beer and sit in the tub. Winter tubbing is fantastic.
And who says you can't have both a hot tub and a pool?
A quality Above ground pool is relativly inexspsensive. ($3K and up). Honestly, rather than go with a $11K tub, get a 8K tub and an above ground pool.
As far as setting the temperature down, while the control panel will let you set the heater all the way down to around 80. An insulated, covered tub of water in the sun, wont drop below 90 in the hot summer sun - regardless what you set the temp too. You could unplug it, but the insualted tubs are not going to cool you off like a pool.
Most folks can't get the temps under 95 in the summer. So, don't think you'll be soaking in chilly water in the summer. IF you read these forums, you'll see a lot of folks have a hard time keeping the water temp down.
A hot tub is great, but it aint gonna cool you off like a pool. Just so you know.