About property value... I live in Westchester county, and the property taxes are "communistic" to say the least (I don't mind,) and a pool adds to that. Hence folks here, unless you're really loaded, tend to join private clubs or the local town pools. I don't like to drink someone's piss, so my own pool is my only option. I have the added benefit that my property, or at least the section of the property where I'm thinking about putting the pool in, is on a slope, and there's a tax break for that.
That and the fact that, were I to put the house in the market, having a pool would set my house apart from the rest because mine would be the only one with a pool (at a certain price range of course).
And we all know that a beautiful woman with big tits beats (no pun intended) a beautiful woman any day.