Thanks everyone for your replies.
Yes there are four of us. I know that makes it tough. DS graduates college that spring (2022) and we're hoping to go late May/early June. We want to make it a special trip because I know after that family vacations are going to be harder to come by. With there being 4 of us, I just don't see us earning enough of one reward currency to do round trip so I think we'll have to split it up. I'm thinking we are going to go for earning Delta and AA all while trying to accumulate UR/MR as well. At least we have two years. I would love to pay for it all with rewards but with there being 4 of us I'll just be happy to do as much as possible. We fly out of Pittsburgh but that doesn't seem to be a great airport for flights to Europe. We like Baltimore and it's not too far, so I could see us flying out of there and it seems Baltimore has a lot more options.