I agree with most of the other folks here. Use smaller lenses. You'll annoy your family and others if you have a big, white lens.
The 24-105L would be a good one to rent, although it won't be as good in dark places.
I took the 18-55 and the 55-250 two years ago. Got some cool shots with both. But next time I won't bother with the longer lens.
This is a mediocre pic, but I show it because that's the best darn food in the park. It's at the Animal Kingdom (I forget the name, but it's pretty much North African and Middle Eastern food). Supposedly there's a long wait time for reservations (days, weeks, or more), but we called ahead and got in and it didn't seem very crowded. The food was really good. Pic was taken with the 18-55 handheld at 1/15.
This is another 18-55 of the wife and kids. My wife was posing but the other two weren't. My wife was happy to get off her feet and enjoy some wine in "Germany." I love Epcot the most. Little kids aren't as into it.
Here's one where a bigger lens might have helped. The Indiana Jones Stunt show at Hollywood Studios. I got invited on stage and was in the entire show from start to finish. It was fun and you could definitely feel the heat of the explosions. This was a warm-up scene in which they get us to overact. I'm one of the three guys yelling in emotional pain as our friend lay dying. I'm the one in the middle with jeans and the headwrap thingy.
Finally, this was in "France" at Epcot (note: There's a pastry shop there that sells Napoleons for five bucks. Totally worth it. Huge and delicious dessert). I found this fake old camera and props (bolted to the ground), bought a beret (made in China) and made my wife take a picture of me looking cool/dorky.
None of the shots I took with the 55-250 are worth a darn. Mostly family shots with the 18-55, and it was usually set at 18mm.
To get good shots, use a wider angle and get close to your subject. Fill the frame with people. Good memories that way.