Will be in mobile for about a half day. Just looking for suggestions on to do's, best local type food, etc........

You can tour the USS Alabama if you're interested in that. There's also Bellingrath Gardens. It would help if you indicated what you're interested in seeing, etc. Local seafood can be found at the restaurants along the Bay right by the battleship.

http://www.ussalabama.com/
http://bellingrath.org/

If you want cute shops, etc. go to Fairhope.

We were in Alabama in March. Bellingrath Gardens is beautiful and worth a visit if you're at all interested in flowers, landscaping, fountains, view of river, etc. The food at the café at the Gardens was actually quite good, reasonably priced, and they served us banana bread made from bananas picked in their greenhouse that morning.
We thought Fairhope was pretty disappointing and didn't have many shops that were at all interesting or unusual. Not worth a trip in my humble opinion.

Not interested in museums, art, gardens, and similar. Is there a main street walking area?

USS Alabama is an idea, but we can do that around where we live.

Just looking for casual, local stuff, southern or gulf coast type things. Just looking for what people suggest...

My wife and I found really nothing to do in Mobile and are glad we did not stay in that area and actually were glad we took extra time to drive around Pensacola that same morning. Ate at the Oyster House, my wife loved her shrimp, my stuffed flounder was okay.