Here is a fun and helpful link for WDW regulars visiting
Disneyland:
http://www.disboards.com/showthread.php?t=1162599
My main recommendations are to make sure you ride Indiana Jones and the Matterhorn since both are unique to DL. Also, the Fantasyland area in DL is a bit different, its more charming than the MK's. It also has several rides that are unique to DL:
Alice in Wonderland
Pinnochio's Daring Journey
Mr. Toad's Wild Ride
Storybookland Canal Boats
Casey Jr. Circus Train
And Matterhorn which I already mentioned
Disneyland doesn't have a Liberty Square but it does have New Orleans Square. There are some really good full and counter service restaurants in there including the Blue Bayou which is right inside the Pirates ride. And speaking of Pirates, the one at DL is about twice as long and much better than the MK version. DL's Space Mountain is also much different and most people think its better than the MK's.
At DCA you will want to see the Aladdin Show for sure, its incredible. Also there are plenty of rides unique to that park. I love the new Monster's Inc. ride as well as California Screamin and Grizzly River Run (like Kali but longer with two big drops instead of one).
DL is much more compact but that can be a very good thing. Park hopping takes about five minutes since the parks are located right across from each other. You can eat at DTD or any of three onsite hotel restaurants very easily since they are all right there as well. You will have lots to do and your WDW knowledge will help you maximize what you ride and see. Have a fun trip to Disneyland!