[Disney Den]

My DH is desperate to go to Disneyland next year in August and I just don't really know where to start. We are a family of 4 (me, DH, DS age 15 and DD age 13). We will probably book 14 nights. How many days will allow us to do Disney to death ( bearing in mind we are going to WDW in August for 3 weeks and intend to spend every day in a Disney park on what will be our 10th visit)? DH is very much into the history and likes to take everything in without racing across the parks from one attraction to another so I would want to allocate sufficient days to do this comfortably.
I'm assuming it is best to stay as close to Disney as possible within our budget and then to move on to somewhere else for the rest of the trip. I have heard LA is not so great but having never been before I would like to see some of the iconic sights.
Some guidance on how I should plan my trip and what to do would be gratefully received as I'm feeling out of my depth.
Many thanks