We're doing the same thing. My oldest DD is graduating High School this year, and it's just been miserable for her. We origianlly were going on a family
DCL over spring break, but when it became apparent that wouldn't happen, we changed gears and asked if she'd have fun going with her Bestie.
The only hangup is that my eldest will be two weeks shy of her 18th birthday when they go. Bestie is 18 so the reservations are all in her name for a studio at BLT. Thanks to the ticket offer, they're getting 6 days instead of 4!!
But between DW and I, there was a lot of "heck, can a 17 yo fly by themsevles(yes, most airlines allow 15 and up to fly on their own), or can a 17yo checkin(the answer is no, and that's why the reservation is in Bestie's name)."
We felt that WDW is probably the safest place we could send them to on their own, as it is a bubble, with internal transportation. I'm just happy that we have the financial means to do this for them. DW and I were humbled when we broached the subject with Bestie and before we could tell her that we'd take care of all the expenses, she got a sullen look on her face and said there'd be no way she could pay for it. That look when we told her we were paying was priceless.