Yellowstone and Glacier in May

Besides the weather, you've already heard "Too Much", that's because you can spend a full week at Yellowstone alone, Glacier is another 4-5 days, Badlands, Custer, Rushmore, and Wind Cave (plus Jewel Cave), another week, Tetons/ Jackson Hole, another 4-5 days, Crater Lake 1-2 days depending on what you want to do, Yosemite, 3-5 days, depending, Sequoia/Kings Canyon, 3 days, of course None of this includes drive time. Now, I know some here will say you can see all this in less time, but I can tell you if you try to rush through this list you're not going to see much or enjoy it very much, ie: I read on here one time that one guy said he did Yellowstone in 1 Day !!!:S
After being there for 10 days I can tell you for a fact, he didn't see much of anything. If you don't want to do anything, or see everything, YES, you can spend a lot less time at each of them.