Jen, I have to agree with this advice. (Please understand that I'm originally from Vermont, so what's pleasant weather to me might well be chilly for you!) Plus, it's less mobbed in May. Hotel prices rise during cherry blossom time. (But, on the other hand, the blossoms are very beautiful . . . .) For my $, May or late September are best here.
Thanks for the travel advice. I appreciate it. No kids to travel with, so dates are wide open.