I go every year for Memorial Day, It is close to 5/27.
It does get busy from the Friday to Monday but nothing compared to Christmas and the 4th of July. I have seen wait times at the Mountains at MK for between 45 min and 1 hour.
5 more days for my yearly birthday trip to see Mickey. Peggie
We were at WDW last year, arriving the day before Memorial Day. Tip? Go to Epcot on Memorial Day. It didn't seem at all crowded (except that there was a long line at the security checks).
That may have been true last year, but the difference this year at Epcot is that <I>Mission:Space</I> is open and that may draw the crowds, especially first-timers.
But I agree that Epcot will likely be the least crowded of the parks so that's the place to go on the holiday.