Wow, Maybell. That road trip you took with babies is really impressive!
Ok, logistically, I'm not sure how I would manage an airplane/car rental trip. Maybe when she is a bit older and doesn't need a giant car seat anymore, that is definitely do-able. But it is tricky to do single-handedly... It's possible, but tricky. I once saw a mom traveling with a baby in an ergo and a pre-schooler, with a giant guitar on her back as well! So, anything is possible, I suppose.
As for what makes a trip fun? Of course I love spending time with her-- but she also loves hanging out with other kids, and frankly it's nice to have some adult conversation once in a while, too...