Congratulations to your son!
My son had the same decision to make. Once the offers are in hand, it makes the choice very difficult. He had other decisions regarding multiple ROTC offers and scholarships, but it finally boiled down to USNA vs NROTC.
The first thing he did was to accept NROTC and know that he has a place to attend college. That is a very good feeling, as a kid and as a parent. He does not have to formally accept the university with a deposit until May. If he decides to send in the enrollment deposit, read all of the fine print about refunds or any other commitments that are non-refundable (such as dorm fees, etc.). We sent the enrollment deposit knowing that it was non-refundable but we did not sign up for housing, because that refund was not guaranteed.
When the appointment letter came in March, son took 2 weeks to decide to accept. He had already visited the schools he was choosing between and had spoken with many ROTC officers, Navy officers and recruiters to find out as much as possible about not only the schools but also his future. He also browsed admissions websites to see majors, courses, activities, etc.
He decided on USNA and kept his NROTC scholarship and school until Induction day. Anything can happen between now and Induction Day, and injury was in the back of our mind. He notified NROTC unit and told him his plans, they did not object. The day after Induction Day, I sent NROTC and school his decline.
Son was nervous and excited to attend USNA and was worried about the 'normal college life' that he was giving up. LOL! He has had more fun since July 1st than I would have ever imagined. Yes, it's hard and exhausting, and challenging, but he takes advantage of everything that USNA has to offer and I believe that to be the key to success.
Church choir and a good since of humor, healthy body, and a never ending supply of cliff bars got him through Plebe Summer. Since then he has studied hard, learned the system, found his sport and activities, attends away football games, has been camping, and has made more friends in this short time than most people make in a lifetime.
When he calls home he is excited, exhausted, determined, and driven to make the best of his time at the academy. My husband and I have been so happy to watch this evolution. His biggest frustration right now is deciding his major...but I assume alot of kids are having that issue right now.
Your son will make his decision in his own time. Make sure you give him as many resources as possible so he can make an informed decision. Has he visited the schools, spoken to grads, ROTC officers, midshipmen?
I truly think the kids are scared that they will miss out on something if they choose USNA. I suggested to my son that he also think about the day after college graduation and look at where he'll be. Factor that into the decision.
Kids will make their college experience what they want it to be. Civilian school is defintely no picnic, either.
My son is having an extremely positive first year and he has made it so. A positive attitude helps.