Made the trip to California last September(from ETex) for UCLA game and our Grandson's graduation from Boot Camp (4th generation Marine). We were gone longer than the time you will have , but you can make it a fun trip. Your son's graduation will be a hi-light for the family and especially for him having you there.
There will be several thousand people at graduation, enjoy.
Total trip is about 3500 miles (1500 each way and add 500 for run around there)
We stayed at a Marriott in Old Town right next to MCRD (about $125 a day). The facilities on MCRD are not A/C. Also, 3 nights in the BOQ at MCRD (limited to 3 nights for retired Officers) so Old Town for 3 nights
We spent 2 days at Disney, stayed at a Marriott Towne Place for actually about $100. It was not far from Angels' baseball stadium. And we had 2 nights in Spring Hill Suites in Pasadena for game.
There's a lot to see going and coming, as some one has already mentioned, but also a LOT of nothing, but you can make it a great trip for the kids. Will add some miles and hours to the trip, but will break it up and make it more enjoyable.
We try to keep our days travel to no more than 450 miles, so that 3 days/2 nights to San Diego and same back.
For us it was 5/4 as minor league baseball was rapping up and we made games in Midland, El Paso and Albuquerque.
Being Marriott Rewards members , we actually recovered, through points and promotions, half of the nights we stayed in motels. So if not a member, JOIN. Out and back, we stayed in Midland, El Paso, Las Cruces, Albuquerque, & Yuma.
One question, is your son taking leave from Boot Camp? Is he returning home with you? Our Grandson rode home with parents and with you already have a car load, would make it tight. Especially with all his junk!!!
Plan it out and it can be a great trip and will make that son smile even more on graduation and earning the title, MARINE!