Wife and I each had MileagePlus Explorer cards. Last year, on our first renewal, we were offered something like 10K on a $1000 spend. So we kept them.

This year, for both of us, the agent said she couldn't offer us anything. So we cancelled. I used the card infrequently, averaging perhaps 1 or 2 car rentals a month (for the better insurance). I don't think my wife used her card at all after meeting the $1K spend.