My D went to both the Campus Visit Day in February and also Admitted Students Day last year. If you are at all concerned about weather in the North East I can recommend the Campus Visit Day as it was a gloomy day, where students were definitely well ensconced in their classes so it was not a real frolic. D attended actual classes in addition to the forums that explained very well the Div I- III system as well as the heavy emphasis on writing and revisions for many academic classes. If you have not visited before, it may be a really good experience. There were both juniors as well as applied but not accepted seniors there.
The Admitted Student Day was also lots of fun, but much more rah, rah and the profs would give mini classes, seminars, presentations about a particular class or area of study. That was interesting (and funnily enough my D ended up having both profs as first semester teachers that she observed on Admitted Students Day- even though in choosing classes you don't know who teaches them when prioritizing your choices in the summer.)