I have attended both NASS and, essentially, a CVW (official sports visit; emphasizes the sport practice but still shadows daily life of plebe). At this point, since you don’t know if you will get accepted to NASS, it is safe and smart to accept your CVW. However, having been on both, I feel NASS was more worthwhile.
Both visits are completely different. NASS is a fun, and sometimes scary, way to “become a plebe” and feel out the academy. It is cushioned, however, to appeal to the candidate. Notable to mention that it is competitive to get in, and after doing the math last year, it was around a 17% acceptance rate for my area (Northern VA- highly represented. Arizona not so much so you prob have a much higher chance of getting in.)
As I stated before, a CVW shadows the plebe.
Now, I have had a brother who graduated from USNA and completely described academy life to me, so my conclusions about a CVW are drawn from that in addition to having attended NASS first. There are things you will do at NASS that you won’t get to do at CVW, but there aren’t any things I can think of that a CVW provides and NASS doesn’t (other than real life plebes). Having said that, nothing at CVW surprised me. I feel like I got a really good feel for the USNA at NASS, because at NASS you eat in KH, do PT, and attend classes-which is basically the premise of a CVW.