Something tells me he's into Orange's, Lemon's, and Lime's.
Your first two options sound more like pleasure than business, and the 737 type would mean pro, but if you aren't going for SWA then I wouldn't waste my time/money. But the same can be said for the seaplane ratings unless you plan on working in some capacity with those planes, or owning one.
I'm thinking I'd save my money overall unless it's just burning a hole in your pocket. I would love to do the SES/MES myself, but I can't justify the means since I don't see myself using the rating in the near or distant future.