I've been to DL alot and WDW just once 20 years ago. So I can't really compare the two. I can tell you that I think since DL is the original, I think you should definately ride matterhorn (the line to the right, not the left it's better on the right) and It's a small world. Also, they just redid Space Mountain. My favorite ride is Big Thunder Mountain, so I always have to do that, but I did it in DLP and it was much better than DL so there you go. At California Adventure, I recommend eating at the boudin bakery. They have a soup/bread bowl...YUMMY! We always eat there. If they don't have California Screamin' (or something similiar) I'd do that. It's a roller coaster and it goes upside down. Also, on the Rapids in CA, you get wet....really wet..so be advised. As far as the parades go, the best spot IMHO is in fantasy land by the mad hatter and alice in wonderland or down on main street. The Best spot in CA for the Parade is up at the top by boudin. There's a large space up above the rapids before you enter the boardwalk area, plenty of seating and good views. I don't recommend being down by the golden gate brigde...it gets WAY too crowded there. Don't forget if your staying at the Grand or Paradise Pier, you can enter CA thru the Grand entrance, not at the front. Just bring your charge card for the hotel with you.
Hope that helps.
Steph