Last weekend was the weekend I went to the Elroy Sparta trail. We stayed in Wilton at the village campground I mentioned above. As CPcyclist mentioned, they do the pancake breakfast. Showers are a quarter for 4 minutes, so I'd suggest bringing 2 quarters per shower. The pancake breakfast was $5 for juice or coffee, 2 sausages and all the pancakes you can eat, on Sunday. The campground has a portion that is all RVs packed in super tight, and another portion that is more spread out with just tents. If anyone wants to see my pics they're over here:
https://picasaweb.google.com/116288651905699248553/ElroySpartaTrail?authuser=0&authkey=Gv1sRgCNnGp7bim97hVQ&feat=directlink
The campground is very open, unlike the DNR campgrounds I'm used to staying at. Given the options, I think this might be the best bet if you're staying in one place. We did the whole trail, went to Elroy on Saturday and Sparta on Sunday. Almost made it to the long tunnel on Friday but turned back.
Funny thing happened.
Once we decided to turn around and ride back to camp the first night, I told my girlfriend "go on ahead, I'll catch up" because I wanted to hit the lap button on my garmin and I wasn't sure how it worked. She took off, and eventually I got going again. I was screaming down the trail when I saw her sobbing, holding her bike with her back turned to it. She said "get it out, get it out" and I thought something got stuck in her eye. It turned out a squirrel tried to run across the trail, but wound up getting caught in her spoke. Needless to say it was dead. I guess thats a word of caution though, I wouldn't think you'd have to watch out for stuff like that.