The Rockford Speedway is a short track (~1/4 mile) for racing all types of cars from road runners to late models. Have been there several times (with family) and I should say up front that I'm not really a racing fan, hardcore or otherwise, this was just something to do. Sometimes the races at RS are really exciting, and sometimes really super boring and completely uneventful. The majority of nights tend toward the latter.
Best part: Trailer races of destruction (regular and figure 8, twice a year) are pretty fun to watch. Tickets aren't too expensive and it's easy to get to, but try not approaching directly from the west (down by Kohl's) to avoid six degrees of traffic light hell. The east or Perryville Rd. is probably best.
Worst parts: 1. The bathrooms. Terrible. Not clean in any way. Small. Smelly. Crowded. Look as if built as an after thought. 2. The crowd. Sometimes terribly rude with smoking and obnoxiously drunk. 3. Food. Food is a little on the expensive side for the mediocrity of it. 4. Seating. Most is general, choose your section, unbacked bleacher seating, which gets uncomfortable quickly - and the night may be 3-4 hours long. Bring a seat cushion if stiff metal seating bothers you, and don't be afraid to get up and stretch frequently. It's also very loud at times. Bring ear plugs for your family. They do sell them there (no assurance of availability), but last I saw they were a dollar a pair. You can get them much cheaper at an outside store. Also, as the night goes on, it can get cold, so dress appropriately for weather as the place is outdoors. Parking is also difficult at times, in the grass lot out front. Long walk to the door. Get there early for a better spot.
All in all, a trailer race night is probably the best entertainment value for the money, and still tolerable for non-fans also. Although, to see this event, you may have to sit through 3 hours of boring races with one crack up which takes a half hour to clean up. It's not Le Mans, that's for sure!