On lap swimming, as I mentioned earlier, I previously had a 28 foot pool. I thought this was a very nice size for general pool playing, big enough that it never seemed crowded, yet small enough that it was easy to take care of and heat. My opinion on lap swimming, you could swim a few laps, sure, but I wouldn't really think that swimming a regular workout in there would be a ton of fun, so much turning around. A mile in a 29 foot pool would be about 180 lengths, or if you count a "lap" as to the other end and back again, then about 90 laps.
You could of course swim from corner to corner in the pool rather than end to end-- the hypotenuse that is. You'd get roughly an extra 4-5 feet per length that way and would cut a mile down to about 78 laps.
Obviously you have to keep in mind shallow end depth and your arm length-- you don't want to be scraping your hands on every lap.
Seems kinda hard to say what I'm thinking, and this is just one person's opinion: if in your mind you're thinking that every now and then you might like to swim back and forth a little bit to get the 'ol blood circulating, probably 29 feet would be fine. But, if what you're thinking is that maybe this pool could also be a great platform for exercise, and maybe you'll want to start swimming laps for 30 minutes every day for the long term, well if it were me I'd try configure the pool more to provide a bit more length, and sufficient depth for that.