There are a couple things to know.
It is during off season so while that sounds like good news keep in mind that DL always has busy weekends.
The worst thing is, because May is about a month long off season. End of Spring Break to Memorial day weekend, its the second longest off season DLR has so rehabs of major attractions are possible and likely.
I wouldn't expect to do a lot of DL on part of Friday, because Friday night is busy as locals get off work, and Saturday.
So if me I would really like to stretch it out and get in on Thursday and enjoy a quiet day in the park.
Also while nobody knows when Carsland will open in DCA. If it opens early in 2012 this could dramatically effect crowds.