The more the merrier, I always say. If it's just for commuting/riding around town, there's no reason not to get 36, at least on the rear. I'm significantly heavier than you, so YMMV, but if you're not concerned about the weight of the bike, you'll have a stronger wheel with more spokes - all other things being equal - so why skimp on spokes?

32 would be fine at your weight, too, if you find a wheel you really prefer that only comes in a 32 spoke configuration and not a 36.