One of the best trips my mom, a seasoned traveler, gave me, is to pack in colors so you can more easily do laundry. For instance, if you bring three red shirts, three white shirts and four blue pairs of pants, you have a bunch of little loads. If you concentrate on bringing blues and whites, for example, you will have two full loads. I thought that was brillant, because I hate when I have one or two pieces I have to wash because they are central to my wardrobe and they are an odd color. We are DVC members, so we can do the laundry in the room and it's really not a problem.
Another tip I have is that I pack the kids clothing in baggies by temperature and event, then write on the outside what it is. For example, "warm, dressy" or "cold, casual" I also then coordinate the three kids clothing. I do this because then the kids are in outfits that compliment each other (not necessary matching, just the same general colors) and any picture we take is a fantastic one. It also makes the kids easier to pick out in a crowd and it is amazing what purposely gets left behind when I start packing this way. It is amazing to me how easy it is to overpack, thinking you will need a ton of shirts, etc., but when you break it down you need much less than the original "piles to pack" that you might have made. I also bring a few extra shirts, etc., but I wind up with far fewer odds and ends. It cuts down on my packing volume and it makes it really easy for my kids, or DH to pick out the kids clothes for the day. It does mean a bit more work packing, but it ensures I have the right outfits for each situation and it is so much less stressful at the park.