I'll go one further on Comtessa's list, the bathrooms are all near the luggage racks, so leave all your poopy-diaper only changing stuff down there. Give yourself a ton more room for the toys your baby'll ignore

The seats at the ends of the car can be flipped around so you have a seat facing a wall with a good amount of room. Plenty of space to lay down a blanket with toys and such. With a crawling and/or non-mobile baby that might be enough. (Sorry, can you tell my toddler took one look at my lovely set up and went "as if!"?

)
A huge

about water bottles. Bring as many as you can carry slightly uncomfortably. Don't break your back or anything, but better to feel sore and have that next water bottle.
At night, be ready to bring one of your medium sized bags upstairs to put at your feet. The leg rests are wonderful, but just slightly too short for really comfortable stretching out. Being able to extend your legs all the way makes a huge difference to comfort at night.