I just got back from a whirlwind 46 hour trip to DL for the DL ½ marathon weekend.
Take advantage of the single rider lines if you are touring solo.
If you can wait to eat until later, dinner at The Plaza Inn is tasty and you can sit and enjoy the fireworks with a castle view--without staking out a spot early and having your limited park time tick away.
A lot of DCA is under construction. I was told this multiple times and shrugged it off. It makes the park seem even smaller than it already is.
If its within your budget, do the World of Color dining package at Ariel's Grotto. You will get preferred viewing for the show and not have to line up for a FastPass for it nor get to the general viewing area really early to line up to get in. Second show is far less crowded if they have two shows.
Look at your park map and times guide, preferably before you go in the park, but also refresh your memory while waiting in line. Have some idea of what are your star attractions.
The FastPass machines are not synced between the parks and the Roger Rabbit ride in Toontown in not on either parks' system, so you could effectively be holding three valid FastPasses at once. (If you had the park hopper option.)
DL's Fantasmic puts the one at the Studios to shame.
Downtown Disney is a better overall experience in California.
Check out the Aladdin show in the Hyperion Theatre in DCA. It's a great show and gives you some down time to rest your feet.
You have to go through bag check just like you do at WDW, but it is to enter the area where the park entrances are. They do
not have a line for "No Bag" like they do at WDW and that can back you up.
One of the bars in the Grand Californian, The Hearthstone Lounge, is extremely friendly.
If you know anybody local that is an annual pass holder and wants to play tour guide, that is helpful too. Thanks Chrysty!
Chat up people in line too. You never know who is a cast member and wants to share the magic of their park. Thanks Ty!
Thank you so much. These are some great tips. 
