Well, I did move out of state with my daughter. He gave consent, so I would say our situation was a bit different, and he wasn't seeing her AT ALL and he lived, literally, down the block.
I don't think you have a valid reason to move.
I think it's in the best interest of your kids to have a relationship with their dad. Even at the expense of a "not-as-good" education. A solid relationship that is even every weekend is BETTER than no relationship and a better school.
Can you find them a private school to attend that doens't move them away?
Kids who have stable relationships with both parents get in FAR less trouble. They have FAR less emotional struggle and the impact is FAR less than kids who have a severed or unstable relationship with one parent. If they are girls, they are less promiscuous (didn't research effects on boys, cuz I don't have one) if their dad is stable.
If he's seeing them EVERY weekend...... potentially that's Friday night - Sunday evening. That's about 2.5 days a week - which is like 30% of the time. That's NOT an insignificant amount of time to spend with them.
If he says he can't spend more time with them.... is it because he is working? Does he pay child support? Does he provide "extra's" when it's his time with them? like clothes, or shoes or whatever when they are "out"?
Do you make it difficult for him to spend more time? ie - nagging him to do things your way, or dictating the times he can come over.
He may make up for the things YOU feel is important in OTHER ways when he is with them.
They won't care if he goes to their basketball game (or whatever) if they at least get to see him.
You could try to work a deal with him.... What are you willing to compromise on? It sounds like you are expecting him and your kids to make all the compromises?
YOU will pay for all transportation costs. He can have them EVERY holiday and 10 weeks in the summer. If he sees them even 2 days a week now (assuming).... then that is roughly 100 days a year.
14 days at EVERY Christmas
5 days at EVERY Thanksgiving
7 days at EVERY Spring break
(10 weeks x 7 days a week) if he gets them almost the ENTIRE summer
That's 96 days.
Are you willing to give him that much? And you've made it difficult for your kids and him in the process, because if he doesn't have time during the week now, he won't in the summer... so, who will they be spending the summer with? You would have to adjust to account for child care in the summer etc.
I don't know how old your kids are..... if they are 13 or older, they will be able to fly unaccompanied without the extra fee to see him for vacations.
Just my $0.02