Jericho and I took a quick bike trip out of the city a few weekends ago.
The Minuteman Campground is pretty nice. It's still fairly early in the season, so there were only a few other people there. We brought a tent, but there were also campsites with cabins, which might be nice for longer trips (ie, less baggage).
The ride out was about five hours (including a stop for lunch). Coming back was much quicker, maybe three hours (including a stop for lunch and ice cream).
Overall, a fun trip.