If you have a good credit score and can hit the min spends, I'd say do:
1. the two browser trick for Citi
2. then maybe the starwood personal and biz cards
3. if you're feeling up for it the chase sapphire preferred and ink bold from chase

This would net you quite a few miles. Not to mention you'd be able to transfer the SPG to many airlines and the ultimate rewards to UA, for example, and have miles in multiple programs that allow one ways (in case there's an issue with availability). Always good to diversify.