Luggage and bags:
Bring a sensible bag with only the necessities. It's a pain making trips to and from the lockers at the main gates or all the way back to your room if you're staying at one of the Resort hotels. We use the lockers when we make a full day trip and want to take extra clothes like a jacket or sweater to wear in the evening. Like many things at Disneyland, it's not cheap to get a locker, but it's way better than carrying things around that you don't necessarily need at that moment.
Clothing/Shoes/Weather Gear: While at the Disneyland Resort, you will so a lot of walking...A LOT OF IT! Don't ruin what should be a magical day bu wearing the wrong shoes just because "they're SO cute." You'll have a lot more fun if you leave the stiletto heels at home. Comfortable clothing is also a good idea. Weather aside, many of the rides in the parks are NOT conducive to miniskirts, no matter how cute they may be. You may be a lot less cranky at the end of a day in the park if you dress comfortably.
Toiletries and Medical Supplies: Weather and stress can make for a big headache when you're trying to steer the entire family around the Disneyland Resort. Bring travel size medicines like Tylenol or even Pepto Bismol may be the difference between a wonderful trip and a nightmare.
Okay, if you are going to spend a day at Disneyland Wear Comfortable Shoes! Yes, I know this sounds like it would be a no brainer, but I can't tell you how many times I have been to Disneyland and seen people with what have got to be the most uncomfortable shoes ever. Women in heels, guys in thin-soled loafers, etc.
Wear sneakers, the thicker the sole and the more comfortable the better. You will walk for miles without even knowing it, only the blisters on your feet and the fatigue in your legs will clue you in at the end of the day.
swimsuit, shorts, long pants=chilly at night or on water rides, bring plenty of 'spare' clothes, socks, etc....
Camping/Beach/Outdoor Gear: beach towels, sun tan lotion, especially for the face whatever time of year!
Miscellaneous: Good Walking shoes...OMG...GOOOOOOOD WALKING SHOES...LOTS OF WALKING AT DISNEYLAND ...LONNNNNG LINES!@!!