After two and a half years I've finally found an easy way to change the sheet on my sons' crib mattress.
Lift one end of the mattress way up, leaving the other end in the crib. Put the sheet around the top end and then lower it back down. Then lift the other end of the mattress and put the sheet around it. Put it all the way down. Pull and tug on the sheet in the middle until it's taught.
Let me tell ya, if someone would have told me this early on, I would have been a lot happier. Instead I wrestled that stupid mattress like a 10-foot alligator, in the crib, out of the crib, etc.
Oh, and while I'm on the subject of cribs, the breathable bumpers are wonderful! You can find them at www.onestepahead.com. They are not bulky yet they still protect baby from bumping up against the hard rails or getting a foot stuck in between. And they are cheaper! And they match everything because they're white! I wish I'd have invented them...
Both of these ideas work for me!