Besides taking care of friends and family, I'd buy all the abandoned or nearly abandoned malls in Northern New England and then pay off PB's and ZBA's to allow housing (talking to you here Newington) and stock it with affordable housing (somewhere between 60 - 80% AMI). Some, but little Section 8. I'd put in covenants that made them affordable in perpetuity.

Also, I'd probably buy that awesome property in Kittery a few houses before Seapoint Beach.