Hi there @Michael Galesky, I'm stationed at WPAFB right now! Feel free to shoot me a PM if you/your son have any questions about the area!
I'm pretty rookie myself but from talking with others, the market here is good but not "red hot." There's a surplus of housing (mainly SFRs).
I don't know much about the multifamily route but there's the AFB and Wright State and University of Dayton which all help the MF. There are a lot of defense contracting companies which bring in interns so I think that would help the short term housing as well. I would stay away from inner city areas but there is some industry building up (I think a glass plant just opened up that's hiring a ton of people). The recession hit Dayton hard but it is recovering.
@Darrin Carey and his wife @Christina Carey are a great resource and have orchestrated a REIA here. In fact, my answer probably would sound very familiar to them as it's mostly their advice to me!
We're currently renting so we'll be moving out of our 3/2. The owner might be interested in selling (or your son can rent it, we're getting great deal on it! I also know someone at the REIA is looking at selling their condo in the near future.