If you just want to hit the hight points, two days at DL/CA would do it. If you want to spend a bit more time, plan three or four days. And, remember, those attractions "crammed into Disneyland" originated there, for the most part! It's WDW that spread them out!
The parks are much smaller than those at WDW, which also makes them more crowded during high season--particularly summer. When we were there in July, 2006, it felt like July 4th 1976! I had never seen the park (only DL at that time) that busy at any time prior to that!
There is more detail in Disneyland that the MK, although MK definitely has stepped up the detail in the past few years with renovations. IASW comes to mind--it always disappointed me at WDW until the last renovation. Even if you don't like "the dolls," it's still more of an experience at Disneyland--to me, at least! :)
I've only been to CA once--in 2006. Didn't get to see a lot, as Leu's DD is not a morning person and we weren't able to access the parks without her. Soarin' over California is a tad better there than at EPCOT. Did get to see the Electrical Parade--formerly the Main Street Electrical Parade. Still love that thing! Even though it has been shortened over the years! :D
We always did day trips to DL when I lived there--it was only about a 1-hour drive in those days. Now it's close to 2 hours--off peak! Leu has stayed at the Disneyland Hotel a few times with her DS, DDIL and their two children over the years. Usually just one night, though. And we stayed one night at the Grand Californian in 2006.
The Howard Johnson's just outside of the parks has a good reputation, and is considerably less expensive than the official Disney resorts. And the DL/CA resorts don't offer the perks of EMH the way WDW resorts do, so it's less essential to stay on site. You might want to research that a bit--I'm using 2006 information and memory. And said memory has been known to be a bit faulty at times!
You and your family did a western US road trip before Jon was reassigned to the UK, didn't you? So you have an idea of the distances involved--the California attractions are not as compact as the Orlando area, unfortunately. But combining a west coast visit with a visit to Hawaii would be eminently do-able, and give you a travel break in the process.