Originally Posted by LAX UA 1K

I'd say UA or CO (which will be combined probably in 2012).

Based on UA: If you get the right Chase UA card you'll earn elite qualifying miles for your ticket purchases (I think on either UA or CO's site) and probably extra miles for all *A tickets. Or if you spend over $35K per year, you can earn 5-10K EQMs on the high priced credit cards (which give either economy plus access or lounge access). All of those cards also offer the option to redeem miles to increase your EQM count from 1-5K additional. So it is possible you can make Premier status by using these boosts even with travel in the 15K miles range.

SPG does not transfer 1:1 to UA or CO (to encourage you to get a Chase card) so that is not a good way to build up miles in either program. You are better off using those to redeem in a program that is 1:1, even if you just use it for redemptions (e.g., US).

CO has a high priced credit that earns even more (flex) EQMs and includes lounge access and other perks (kind of elite lite).