OK, I do a slight variant of the previous posters. AA is my primary airline, so I have a UA MP VISA to have points for upgrades on my alternate airline which I fly 1-3 times/year and usually have no status. I use all my MILES for upgrades whether it be AA or UA as I feel that is the best bang for my mile, plus I hate coach. UA MP VISA is my everyday CC. I also have MR VISA which I use stictly for Marriott stays and Marriott related purchases.