Torker Graduate is a nice, simple bike. The 5 speeds might not be a great idea if you have a lot of hills, but I have some moderate climbs in my neighborhood, and it serves me well.

I have a 54cm, and I'm around 5'7". It's a little too big for me, but at the price I found it at on Craigslist, I couldn't pass up. I think you should get at least the 56cm.