I head out there every Feb for a motorcycle trade show at the Duke Expo centre and there's never much to do other than show related social functions.
However, if you're into design take a look around the Hilton, as it is a fine example of Art Deco. While there you can also go up the Carew tower and take in the views.
If you fancy a cheap lunch be sure to get a Skyline Chili on Vine Street... It's a local speciality.
For a more upmarket meal in the evening I can recommend Sung Korean Bistro on Elm Street and for a nice selection of beer and burgers go to Rock Bottom Brewery on Fountain Square.
And finally, if you're a smoker there is a very fine old school tobacconist on Walnut Street.