It depends on what you're into. I've never stationed at Lemoore or Beaufort so I don't know what those are like. I did spend one night at Lemoore but I don't think that qualifies me to talk about it.
Cherry Point/Havelock is...less than stellar. The surrounding area isn't too bad, you can live in New Bern or Morehead City if you want, about a 20-30 minute drive to each. Obviously there aren't as many entertainment options as on the west coast but if you like outdoorsy stuff and want to buy a house it's manageable. Wilmington and Wrightsville Beach are about an 1:30-2:00 from New Bern, Myrtle Beach is about 3-4 hours from New Bern, DC is 6-8 hours away. You can make it from New Bern to Raleigh in around 2 hours.
San Diego is a great town but I don't think I could live there again. There's plenty to do, plenty to see, plenty to keep you entertained, but I've gotten used to having my own house with a yard and not having people living on top of me. Of course it's going to be expensive, and traffic sucks, but if you don't mind that, it's a great place to live. Good weather pretty much all year. I remember driving my Jeep around all "winter" with the top off. NFL and MLB, plus minor league hockey teams. You can get to the mountains in Imperial County in a couple of hours, same for going up to Orange County and LA. I forget how long it takes to get to Vegas but it isn't more than a few hours.
If he gets Prowlers, he'll be at Whidbey Island for less than a year, maybe 10-11 months. Oak Harbor is a small town, much more rural than I expected. If you like camping, hiking, mountain biking, and the like then you'll probably like Oak Harbor. If you don't like that stuff, then Seattle is just an hour or two away. Vancouver is a pretty short trip, weekend trips up there are common. During the early summer the sun is up for about 18 hours each day.