We were at WDW 16-20. Rain might have kept crowds down a bit but there was still moderate attendance. Stand-by at most attractions using FASTPASS was averaged 45 minutes, some such as Test Track were 90. I don't think CM's were at "crowded park" levels yet and they might have been a little light for the attendance. MGM seemed least crowded then AK, EP and MK were just about equal (we mostly toured after 4:00 pm).
Just a note, the days it rained it rained nearly all day, bring ponchos or some rain gear (it is June!!!).