I would not buy a 29er in part because I'm short, and I just don't believe the geometry would be correct for me. The other factor for me is the ease of storing/carrying the bike. A bike with smaller wheels is easier to fit inside a vehicle without having to lie it on its side. Not a factor if you have an outside rack, but we prefer to carry our bikes inside our vehicle for security. I would think a bike with 26" wheels would be a little lighter than with 29" wheels too, all other things being equal.