Go to Genkota Winery (at Mt....
Go to Genkota Winery (at Mt. Vernon exit) and Pheasant Hollow Winery (at Whittington/Sesser exit, about 12 miles south). Both have really friendly people, you can do wine tastings gratis and they have great gift baskets. Both put on Mystery Nights and have Gourmet Nights. Most summer weekends, Genkota has live jazz.
If you are a golfer, Green Hills is reported to be really good. Rend Lake's golf is also very good. If you are staying at the hotels along the interstate, there is a 9-hole course and mini-golf located at the end of the northwestern frontage road, just past Lonestar Steakhouse (Potomac Blvd.) that is really super close, you can see it along I-57/64 coming from the north. You can't get lost.
A trip to the Mitchell Museum (and sculpture park) is really a must if you like arts & culture. In the winter months they have a concert series with nationally-known string quartets and pianists and the summer has the Cedarhurst Arts Festival which draws around 30,000 people and has very up-scale crafts. Things like woodworking, metal arts, glass-blowing, jewelry. (September)
Mt. Vernon has a Tourist Information Center located on the northwest frontage (Potomac Blvd.) that has weekday and weekend hours. My fondest memory? Mt. Vernon is a great place to grow up.