We stayed in B-2, which was on the river and also right by the amphitheater and restrooms. I was concerned that it might be a little too high traffic, but didn't have any problems. As I recall, there were condos across the river from us; no bars that I noticed. We thought the site was just fine and the kids loved being close to the river. Honestly, the prime draw of the Watchman campground is its location in Zion. The site itself was easily the poorest maintained of all the sites we had on a two week trip in Colorado and Utah. All the other parks we stayed in a nearby state park rather than the National park itself (i.e., Kodachrome Basin SP near Bryce, Dead Horse Point SP near Arches)
If you haven't discovered it yet, "campsitephotos.com" has photos of all the campsites in Zion and most other parks in Utah. Here is the photo of the site where we stayed: http://www.campsitephotos.com/campground/Watchman/photos/Watchman-B-002