A lot of visitors go to Vicksburg for the Civil War history. If your a history enthusiast it doesn't get much better. I drove over one day just to look and see what was happening from an historic view point. I left stunned. It's unbelievable what happened in Vicksburg. Words cannot describe although the pictures can floor you. Other than the historic stuff Vicksburg is a river city and there is a lot happening during the summer season. Plus you have the casinos.
Yes there is the Civil war military park and USS Cairo exhibit/museum plus historic murals along the MS river downtown. Also around downtown are some historic homes, the Coca Cola museum and some nice restaurants.
We like Rusty's on the River, 10 South or Walnut Hill for a delicious meal.
Yeah, if you're at all interested in seeing a Civil War battlefield and you can't get out to Gettysburg, Vicksburg is the one to see (honestly, it'd still be one to see even if you've been to Gettysburg and I've seen both).
There's also plenty of antebellum houses you can view, several museums (Old Courthouse Museum [lots of history of the town/war/etc], Coca-Cola Museum [while Coca-Cola was developed elsewhere, it was first bottled in Vicksburg, MS, as opposed to only coming from a fountain], Lower MIssissippi River Museum [actually about the river...not a history museum], and a few more niche things...like an antique doll museum).
You can get some great views of the sun setting behind the Mississippi River bridges and get some good eats at the places PeachBelle mentioned above (among others but those are some of the best).
And yeah, if you're into casinos they have those too but that's not a reason I would stop (I'm not a casino person though).
If you're visiting in the spring there's also Riverfest ( http://riverfestms.com/ ).
Vicksburg gets so many recs due to the concentration of both Nte-vellum mansions/plantations, and the Civil War parks, in the area. Great town, with so very much to do, and so near.
It is close enough to both Natchez, and to Port Gibson, that they can easily be in lauded in a stay in Vicksburg.