Hi Kira,, We too travelled alot pre kids,, and thought we could continue along once kids arrived. First thing that changed was finances,, we found airfare for 5 ( we had three kids) alot different then airfare for two,, and many places insisted we rent one bedrooms suites instead of regular hotel rooms( I guess I mean Hawaii specificaly, which where we took kids a few times when they were smaller)
Secondly we discovered one of our children was not a good traveller. He has varying issues that made travel difficult. So, for years we stuck to close to home, doing RV vacations, Hawaii, and some ski holidays where we rented a chalet.
Europe was something both hubby and I wanted to expose our kids to( having both family and ties to Europe ourselves) , but all the factors conspired to make it not realistic for us as a group.
Until I hit on the idea of doing one on one trips. Cost less ( smaller hotel rooms, only 2 airfares at once) and the ability to enjoy the trip one on one with each one of our children. Trips became a project, each child had to research destinations and find three sites they wanted to visit etc.
I took first son when he was 14, then two years later hubby took next son when he was 14, then I took our 11 yr old daughter( she was younger but handled the whole experience better then older brothers, simply put, she is an "easy" child)
We all had great trips ,, and trips were all different as different kids enjoyed different things.
In a perfect world I would love to do more Europeon travel with our kids, but , our oldest in now almost 20 and on his own, and our next son really is not interested( he has issues, LOL) ,, but we do anticiapate returning next summer with our now 14 yr old daughter. She will accompany us for part of trip, then will stay with cousins in Germany while hubby and I maybe scout out some other places.
I agree travel is great for kids, but not all kids can handle it well( you frankly are lucky to have two girls