DL is definitely worth seeing. It will be much less walking than WDW, but just about as many rides as all of WDW (fewer shows and exhibits, though).
DCA right now has a lot of construction, but still worth a look, although the best things in it (Toy Story Mania and Soarin') exist at WDW. The Aladdin show is worth seeing though, as is the Electrical Parade.
At DL, Pirates alone almost justifies the trip, making the WDW version seem weak by comparison (DL's is about twice as long). DL has more rides than MK, all packed into an area about as big as DHS. Don't miss Finding Nemo (although I think the effects are easier to see at The Seas) and Indiana Jones.
As far as airports, SNA (John Wayne) is the closest, but LAX is not too bad. Be prepared for long security lines going home from LAX though. There are a bunch of airports there - Long Beach (Jet Blue flies there), Ontario, Burbank. Any of these will do, so look at air fares and drive times.
The DL hotels are nice, but you can get a very nice clean motel room that is actually much closer to the gates of the park (my favorite is the Del Sol). Grand Californian is the only one themed like those in WDW - it's like the WL with the service of the GF. DL Hotel is neat (much better in a few years after a major rehab, Paradise Pier is OK, but nothing that special (we've stayed at all 3).
Because of its size, DL won't take as long as a trip to WDW, but there are many other attractions in driving distance. Sea World and San Diego Zoo (90 minutes),
Legoland (60 minutes), Knott's Berry Farm (10 minutes) and Hollywood (the El Capitan a great place to see a Disney film - 20 minutes).
A rental car is a good way to go (they tend to be pretty reasonable too). SuperShuttle is a great option too.
Anyone who loves WDW should see
Disneyland. It has many charming surprises for the WDW vet, and really gives you a sense of how it all began.