For domestic lounges, DL + Amex Plat.
For mileage program, Alaska (no non-stops to LAS, though).
I am planning to switch from CSR to Amex Plat next year. There is a ton of value in that card.
Alaska has a great mileage program which is what attracted me to it in the first place, but here in NYC it is hard to get value out of it.
-J.