S.P.
When I travel I have a plastic container with toys the kids don't usually play with. I'd take some of the kids toys and put them away. By the time it comes time for the trip, it will be like they are brand new. Some kids are easy to travel with. Mine weren't. As they got older I found out it was because they both have car sickness. I give them dramamine to help keep them calm. They are a lot older.
There just isn't a lot for you to do for a baby. One thing is I found if I had my husband sit in the back with them, that helped. My husband doesn't drive. He'd entertain them while I drove. I hope this helps.
Good Luck!!!