We've been going the first two weeks of May for quite some time now. As long as you stick to one of these weeks you should avoid most the crowds and rain. We've only had rain about 5 or 6 times in the last 7 or 8 years. When we went the first week this last trip it only rained one afternoon for a couple hours. The year before we had no rain at all. Once you get to the third week the crowds and rain increase a bit. But it's still not bad until closer to Memorial Day weekend. From the fourth week on into the summer you will find the crowds and the rain increase quite a bit. We love going the first two weeks of May. The temps are in the mid to upper 80's, plenty of sunshine, and the crowds are not bad at all.