Was a club card holder for a year, and also switched to the reserve. I'm only silver, so there are a couple of benefits I got from the club card, like reduced close-in award booking fees and a 2nd checked bag, but as a 1K, the only benefit you get is the club membership.

The 60s gates at SFO are better than the UCs, the 80s and 90s gates are marginally worst but still comparable to the close-by UC. I'm never in DEN for more than ~70 minutes, so I don't use the UC there.

I will say, though, that the IAD clubs are much better than the sad C/D gates, even when the clubs are crowded (because then the terminal is even more so). One of the clubs has the bar in a nook in the corner of the club, with some seats near the bar adjacent to a tarmac window. The layout of that club has many walls, so you don't feel like you're stuck in warehouse with 100 other people, and if you grab one of the chairs by the bar it's almost always quiet and empty.

But I dropped the membership when my home airport was no longer IAD.