I think UR points transfer 1:1 to Hyatt. Nice Hyatt hotels can be had for 15k a night. (Fisherman's Wharf in SF for example). Sometimes Chase has great rates for rental cars.

One reason to keep them is for emergencies. You can transfer to UA if you need to go somewhere at the last minute. You can also use them to book air travel through Chase with a 20% discount (again, IIRC)

What is valuable to you, though, is your decision.