For me, Texas is one of the best places in the country to eat. Aside from the barbecue in Lockhart, Austin, and Hill Country, the Tex-Mex in San Antonio is outstanding. And I can't forget Killen's Barbecue in Pearland, TX, which is probably consistently the best barbecue I've ever had. Note: consistency is key.
Believe it or not, Wisconsin is a great food state. From cheese to lake fish to every bloody Mary in between, they take pride in their local products and feature them on menus as a matter of course, not because it's what the cool kids are doing.
North Carolina is a super well-rounded food state, with everything from barbecue to fine dining to fried chicken and cheese biscuits. They've got a unique and delicious spin on just about everything served on a plate.
Louisiana is an obvious choice, but I would opt for a visit to Lafayette over the more widely-tread New Orleans. Once you discover boudin and fresh cracklin', your life will be forever changed.
Between Pittsburgh and Philly, Pennsylvania has more good food than you could consume in a lifetime of eating. And I'm not sure there are nicer people to be found anywhere.