We've been to WDW more times than I can now remember, but want to venture to the other side of the country for our first trip to DLR.
We were thinking about May or June.
What are the crowds like then? If we did May, it would not be the week of Mother's Day or Memorial Day, but any other week would work.
Assume you are talking about May/June 2011. Your question is a lot more complicated than you realize because so much is happening at DLR during that time.
First, May is off-season and June is high season - except for maybe the first week. That means more crowds in June. Before you decide that May is better, understand that off-season at DLR works differently than WDW - see "What You Should Know About Off-Season at DLR"
www.disboards.com/showthread.php?p=18462889 and "Choosing When To Visit DLR: Summary of High and Low Season and When Each Happens "
http://www.disboards.com/showthread.php?p=36509602
Second, DCA (the second park at DLR) has some new things coming up including a brand new
Little Mermaid ride to open in May or possible early June 2011. Also a new version of Star Tours is opening at DL in that same time. See MiceChat's info here
Disney California Adventure Project Tracker X and
Disneyland Resort Project Tracker II
Third, DLR's AP program is a whole different thing than WDW and the last couple Junes has really increased crowds during the non-blockout times. See "Understanding AP Blockouts and Impact on Crowds"
http://www.disboards.com/showthread.php?t=2365983
Fourth, grad nights happen during both May and June. See "The Scoop on Grad Nights at DLR in May and June" -
www.disboards.com/showthread.php?t=2298400
What are the hours like? Are May and June comparable? Or, if May has shorter hours, would we still get a lot done if there are less crowds?
See "Historical DLR Park Hours, Entertainment and Refurbs" -
www.disboards.com/showthread.php?t=2291124
Also, what is the weather like for those two months?
Weather is normally about as perfect as you can get, IMO.

See "Comparison of Weather For WDW and DLR"
www.disboards.com/showthread.php?t=1711098
Hope you have a magical trip!
Disneyland Resort rocks!
