Baby first trip please help!!

Maria • I`m happily married, & I am a new mommy to a beautiful baby boy & with my new little girl. My life is now complete 💚💜
Sorry post it in the wrong topic. 
So my husband and I are planning on going to L.A for Christmas to visit his grandparents, We have a almost 3 month old baby boy. We are planning on driving over there, but I feel like it's going to be a hard drive for a 3 month  old baby. I was wondering how you ladies handle a trip for the first time with your babies? What do I take?