It's really the processor more than RAM or GPU that determines how Premiere Elements handles 4K video. Fortunately you've got a good, hearty processor.
I can't imagine you'll see any benefit in a jump from 32 gigs to 64 gigs of RAM. Not with Premiere Elements anyway.
Thanks Steve. That is kinda what I figure. I decided to get 64 gigs anyway (16 memory sticks), that way in case one or more fail I'll still have 32 gigs and not have to hunt down matching memory (which will likely be a pain and probably just as expensive as buying 64 gigs now). So maybe I'll do a test and report back.
For that kind of cost, getting the 64GB was probably a good move. If you ever upgrade to Premiere Pro, even while Premiere Pro really doesn't tap memory usage past 32GB with the current release, assigning 32GB to Premiere Pro and letting Windows caching use the rest does indeed help with some workflows (reducing dropped frames with complex 4k timelines and beyond).