I'm 5'6, the hardrock 29 has big tires..that worries me, but has lockout on the forks..which seems good. But would the hardrock SE 26 be better for my height?
This is one of those cases where there is no substitute for a test ride.
The issue of big wheels on small frames is to overlap with the front wheel. I know that nobody uses toe clips anymore but sometimes it's possible to strike the front wheel with your toe while making a sharp turn. That's most likely to happen during slow casual riding or when coming back into the parking lot at the end of a ride. There are a number of ways that manufacturers try to get around toe overlap. Using smaller wheels is my top choice.