POOL ... POOL ... POOL!!!
I have an above ground pool as well and it is great for keeping cool. The money that was spent on the pool was well spent ... heck if you can get away wit an intex pool (blow up or now a light duty frame) it is a great way to go.
As Boni said - a hot tub is for hot water. Anything less than 100º is cold in the tub, I just don't enjoy it.