For budgeting/planning purposes - this is what the first semester travel looks like including optional events at USCGA for those that need to fly:
Drop off at R-Day - usually fly in on Saturday, Sunday optional religious service, dorm tour, dinner on campus. Monday report at 0600, parents get to say good bye for 5 minuets again later at about 1600 after swearing in, go to hotel and worry, fly home Tuesday.
Flag ceremony, around July 25-30 = Cadets go to Mystic seaport for a short 30 min morning ceremony then get liberty at the seaport for 3-5 hours, then go back. Local parents attend, and some fly in, often one parent to save money, especially if they get the usual first letters home from their cadet and the cadet sounds stressed (which is normal to get a first few "why am I here" letters during Swab summer)
They take the phones during SWAB summer so mail is the only contact. At the end of SWAB, phones can be used so contact improves.
There are a few 3 day weekends the first term and most cadets not on duty get liberty, some parents pick a weekend and fly in.
Parents weekend, you get to attend class with your cadet. Most attend, plan on a ticket.
Some parents fly in to watch fall sports, not many but some.
Thanksgiving, cadets get liberty from Tue evening to Sunday, but most return Saturday. So plan on a ticket home for the cadet.
Christmas cadets get leave, plan on a ticket home.
Some parents do not come out at all, and their Cadet reports to R-day alone and does not fly home until Christmas leave. The Academy takes care of the kids that remain over Thanksgiving for example, no problem. Many cadets make friends quick and get invited to others homes that live closer too.
As you can see, you can visit as much or as little as you wish, your choice. We have to fly and connect to get to USCGA, nothing direct and it can get pricey. Hopefully this info will help you pick and choose what works best for your family.
You asked a great question.
Good luck!