I didn't win but if I had...
Besides the house for myself, my mom, and my wife's mom, a couple cars, and gifts to all the family, I'd buy the following sports-related items:
1) First and foremost, Mike Eruzione's 1980 Olympic jersey and gold medal. These sold not too long ago at auction. I find the guy(s) who bought them and give them a tremendous return on their short investment.
2) The Spokane Indians. My local minor league team. Buy them and give the people I've sat next to for the last decade free season tickets and concessions for life.
3) A T-3 Ty Cobb. The best sports card of all-time, IMHO.
And then I'd spend so much time traveling from one beach to another that I'd never see any of these three purchases