Originally Posted by pinniped

With the revised OP and a stated desire to fly between the Bay Area and NYC, your answer is United.

I'd recommend that anyone get the SPG Amex - it's the best primary-spend card out there IMHO. (Other cards have unique threshold bonuses that may be worth pursuing, but no other card that I'm aware of delivers points that are still reliably worth 4-5 cents each on modest Cash & Points awards.) However, it's not a good avenue to United miles. 1 SPG would convert to 0.625 United.