To preface, I know there's no way to truly anticipate for crowds, but I'm sure summer vacation times are guaranteed busy vs other times.

So I'm planning our first trip to Disney world (or maybe land) and our dates are super flexible (kind of) right now. The wife wants to go during summer vacation for the kids, but I am actually super afraid of the summer crowds. I've heard anecdotal stories about people who spend 3 or more hours in line for a ride and never get to enjoy the parks. I was a cast member for the winter/spring of 2007 at Disney World and it's always been my dream to go in the late January/early February for the super light crowds.

So my question is; are there still slow times for the parks throughout the year or is everything pretty evened out 10 years later? Are the summer crowds as bad as I'm expecting? Are the crowds similar in Disneyland vs Disney world? I live in Far West Texas so I'm sure the school is going to fight me taking the kids out of school for 4 or 5 days to vacation. Is it worth the fight to pull the kids out of kindergarten and 1st grade to go during an off season?

Family of 4, staying for hopefully 4-6 days at either Disneyland or World depending on flight expenses mostly.