If you are bringing pacifiers, it might be a good idea to bring along a pacifier clip. I remember losing pacifiers or dropping them and not being able to get to a sink quickly enough!
Another helpful thing I've found is having a blanket with stroller ties. This really isn't necessary for the summer months but as it gets colder, it's no fun picking up a blanket that has fallen off your cold baby in the stroller! I made my own by sewing ribbons to the corners of a fleece blanket (see picture below). Super easy to make or you could look online and purchase something. You also might want to consider a hat with ties. I know my daughter never wanted anything on her head and I had a really hard time keeping her warm when we visited Disneyland in the winter. I sewed ribbons to the hat she is wearing in the picture below.
While we are on the subject of making your trip easier with babies, don't forget a carrier! It might sound like a good idea to simply carry your child around Disneyland or let her sit in the stroller. Until she decides she hates her stroller and you are exhausted from carrying her all day! Bring a carrier!!
If you will be using a stroller, it's a good idea to bring a bag that will fit in the bottom (in addition to your primary diaper bag). You will likely be bringing a lot of stuff into the parks and it will all end up in the bottom of your stroller for storage. Getting on and off the tram, monorail, and Disneyland train usually require you to remove all your items and fold your stroller. This is so much easier when all of your stuff is in one bag. We learned this the hard way. The first and last car on the trams allow you to bring your unfolded stroller on the tram. It's a great option but there is usually a longer wait if there is a big crowd.
The last packing tip I have is for visiting Disneyland in the warmer months. Bring shoes suitable to play in the water. California Adventure has a great water play area for kids. Regardless of age, they must be wearing shoes at all times. Our first visit resulted in my daughter ruining her little leather shoes.
How do we survive the six hour drive?
My husband really dislikes it when I let our daughter eat in the car. Like any other baby, she thought it was hilarious to throw food everywhere. Luckily we're past that stage. But for those of you that aren't, consider an art bib for your road trip. In the picture below, my daughter is wearing a toddler size vinyl art bib. It has sleeves and a couple of pockets on the front. Perfect for baby food in the car! The pockets caught most of the food she dropped and the front completely covered her and avoided any big baby food spills all over clothes and the car seat. Definitely a must have!