I spent three weeks in Puerto Vallarta last year, and I traveled alone. There are plenty of things to see and do, and you don't need anyone to enjoy them. If you're gregarious enough, you will meet a ton of people. Stay away from people who will try to sell you condos and timeshares in Nuevo Vallarta, and especially stay away from the sales people at the airport who will promise to provide you with limo service and other goodies in exchange for a commitment to attend a promo session. It's a hard sell and you're going to hate it. I had the mistake of attending a promo session because I wanted to see if a condo might be a good investment, but it turned out to be such a turnoff that I left the session after 30 minutes. Enjoy!