Try to squeeze in an hour or so to drive around or do a walking tour of Annapolis. Plebes and Youngsters who have liberty from noon to midnight on Saturdays are limited to the confines of Downtown Annaplis (DTA), and the local shopping malls up to a radius of approximately 30 miles from the USNA chapel dome. It can be difficult to find transportation to museums/galleries, etc. in major metropolitan areas like DC and Baltimore, so if your child wants to be able to experience "big city life" on the weekends, it could be a challenge. Annapolis is absolutely charming -- lots of shops and restaurants, state capital of MD, etc., but it is not a major urban center. Getting off the Yard when the opportunity presents itself is a really big deal for some Mids; for others, not so much. Simply a matter of personal preference, but nevertheless a far better local environment than the other SAs. After the first two years, when upperclass have more flexibility regarding liberty, leaving the area is much easier.
Definitely take the tour (the docents do a terrific job) and try to observe a sporting event, even if it's just an intramural practice. All Mids have some sort of physical fitness activity in the late afternoon, so it will give your child a sense of daily life on the Yard.