Flying yourself and a friend means the TY Premier gains a decent amount of value for domestic flights. Once per year, it gives you a companion ticket for free + taxes + some markup. It's marginally more difficult to book through than, say, Kayak, but in a lot of ways it's similar. If you and your friend want to fly to NYC, for example, and the ticket costs $400 ($300 + $100 taxes), you'll end up paying something like:

$340 base airfare
$100 takes x 2
-----------
$540 for two tickets that would have cost $800 to book. $260 in savings is more than twice the $125 annual fee, so that makes the card definitely worth it.

The best part of it is that it doesn't rely on miles or points, so if you have to buy a ticket because there's no award availability, it's there for you.

I always recommend getting it, playing with it, and if you don't think you'll get the $125 value out of it, cancel in month 11.

Other FT members will have a lot of info for you on the best travel programs to South America and Asia, as I have little experience with that. Chase UR points are often considered the most versatile because you can transfer them to various loyalty programs (when you have the CSP)