Also, tennis really is a difficult sport. Don't take a date out to play tennis if he/she is just a "casual" player. Any 3.0+ player can easily double bagel a noob.
I mean you can just casually hit with your date.. but you'll obviously be the better player. You can play a few games and let your date win a few point, but If you're competitive like me you just cannot help throwing in a few winners. I mean they'll definitely try to act like they're enjoying the sport, but it'll just get awkward, very, very awkward... (very true especially if you're a woman!)
Anyways I would prefer that my date/bf would be into some sports other than tennis, so we'll each have our own thing.