You're driving from and to Colorado for a one week college spring break? Quite honestly, even if I was a college student who loved Disney, that doesn't sound like an especially good time to me. I apologize for being negative, but it seems like the time constraints don't work well. Is there any way you could go either over Christmas break or wait until early summer when there's more time? I do understand trying to bring the whole crew along for maybe one last time...once they get out of college, its hard to coordinate anything since they've got jobs, etc (I'm finding it hard to schedule anything together for us, and I've only got 2 kids)
I agree on this part...college kids get done in May, so I'd move the trip to right after they finish and book a longer camping trip - it shouldn't cost much more (camping nights plus extra days are the cheap part) and you can have more time to explore other things than just Disney parks or die...and you'll have more down time between the "drives" (which, with a baby and toddler, will be a killer trip)...
As for what to do with the oldest ones that doesn't cost anything (b/c you mentioned "affording" the trip)...
- Let them set their own schedule...
- Let them have some of their own time in the park - while they might want to explore world showcase, their siblings probably will get bored quickly and ruin it, so you'll want them to be able to have their own fun...
- Get park hoppers...this gives flexibility to your older ones to be able to go to what they like for part of the day and then meet you...
- Have plans for the parts of the day everyone will be together - my family used to meet for all meals and split afterward and then meet for the night shows...you may decide to meet for lunch and spend til dinner together doing the "little kid" desires, giving your older ones the morning and evening to themselves...
- Plan late evening swaps so you and/or the oldest can enjoy some late night fun while some others watch the littles back at the site...everyone knows going in what nights they can have fun and when they are on duty, and everyone gets to have fun. Maybe a night on the Boardwalk, a night at Disney Springs, a night at Citywalk...
- Plan a down day for the oldest to do whatever - give them the keys and let them plan a beach day, a nature day, etc...just tell them to make sure they are back by "x" time. You'll have the youngest all day and you can plan that day as one you spend in Fantasyland or somewhere very, very kiddy...