The rub on all of this is making sure that you gain access to lounges that you actually want to use. I know that, in the US, PriorityPass (Select?) is only good at USAir and Alaska Airlines lounges, along with the few foreign lounges that are scattered intermittently throughout the country.

If PriorityPass sounds like the way to go for you (i.e. you are a US or AS flyer), then you might consider just buying that membership outright and choosing the rewards card that makes the most sense for you independent of the lounge access.