We visit Columbus every July for a trade show. I love Columbus! It's a "little - big town".
Others gave you quilt shop recommendations (which I never get to visit when I'm there - too busy with trade show) but I can make some good restaurant recommendations.
Schmidt's Sausage Haus and Restaurant is one of many restaurants in the "German Town" area (directly south of downtown - a few blocks south of 71 - between 70 and the river). There is also a candy shop in the same square as Schmidts - wonderful confections!!
In the "Arena District" a MUST place to check out is the "North Market". 1 block west of High street and 1 block south of 670. North Market is a co-op of several different food vendors. Some vendors have food ingredients to buy (fresh meat, cheese (the cheese guy is awesome!), spices, etc), but there are a lot of vendors with fresh prepared food to buy. It's a great place to go when one person in your party wants Italian, but the other wants Polish ... you'll find them both there (and more!), plus plenty of desert vendors!! In the summer they do Farmers Markets and Wine Tastings outside.
There are lots of other good restaurants in the Arena district as well ... Gordon Biersch, Barcelona, Rodizo Grill ... the list is endless!!