Update:

I took my bike up to another shop to see if there would be any difference in help. He said that what I was feeling was fairly normal except the vibrating when going downhill. He checked the fork and was thinking the bike was too small. He had me ride it outside in the parking lot to get a better idea of how I rode.

The guy raised my seat almost 4 inches and slid my seat back. I think my LBS had raised the seat and I put it down to get on the bike, but I know they didn't have it THAT high. The guy was really great and showed me how to get on with the seat so high. He still wasn't sure if the bike was the right size but I said the next size up was too big. He said it might help if he extended the handlebars forward some more instead of buying a new bike for now. Nice to know he wasn't out to sell me a new bike when something simple would probably work.

However; just raising the seat and moving it back made a HUGE difference. It didn't feel so wobbly and I seemed to have better control of the bike. He said if I was having problems with it feeling like it was vibrating, bring it back and they'd extend the handlebars for a longer reach.

My LBS doesn't have a much of a parking lot and you have to ride around the neighborhood to see how the bike rides while they wait outside. They really can't see how you ride to adjust to how you sit. They are great, but this store seemed to know their fitting process better.

I also made DH's day as I ordered an Electra Rat Fink cruiser bike while there. He'll get that around the end of next week and he's so excited he can hardly wait. Sigh. The neighborhood is going to think he's nuts.