Welcome back to Disneyland!!!
I went to WDW twice in the 90s and really liked it, but Disneyland is my home park.
As for the number of days, you'll surely get recommendations for anywhere from 3 to 5 days. You can easily hop between the parks multiple times a day which helps to get to things on your priority list more quickly. So you might be "finished" within a few days. However, right now the prices for park-hopper tickets are as follows:
3-day: $265
4-day: $289
5-day: $305
$16 difference between 4 and 5 days... Wowsa. I vote for longer rather than shorter. I just really like to be unhurried at Disneyland.
You can easily fly into any (most?) of the local Los Angeles airports. The closest airport to Disneyland is SNA (aka Santa Ana, Orange County, John Wayne). It's a small airport and easy to fly into and out of... Burbank is further away, but also small and easy. LAX seems to be despised by locals, but I find it an easy trip to Disneyland. I prefer SNA, but will happily fly into LAX to save $$ on airfare or for a better flight time.
We take SuperShuttle when we don't have friends picking us up... $10 per person to (or from) SNA and $16 for the same for LAX. There's also a bus and car service options. Others can guide you on that. I find SuperShuttle to be easy ... Pay ahead online and print voucher at home.
The hotel situation at Disneyland Resort (DLR) is very different than at WDW. You absolutely don't have to stay at a resort hotel to have the full Disney experience. The "Disney Bubble" is something I REALLY enjoyed at WDW, and there are plenty of folks who swear by it at Disneyland too, but it's just not the same.
Search for "Disneyland" on GoogleMaps. When you look at Satellite view, you can see that DLR is in one giant block bordered on the west side by Disneyland Dr and by Harbor Blvd on the east side. Disneyland is in the north part of that block and California Adventure is on the south side. In between the two, you've got Downtown Disney, tram loading/unloading (from parking), and the Grand Californian on the west side. In the center of that middle section is the "Esplande", or entrance area for both parks. The east side has the bus shuttle drop-off and the walkway from the Harbor hotels.
The Disneyland Hotel and Paradise Pier are across the street on the Disneyland Drive (west) side of the park. On the Harbor Blvd. (east) side of the park, you've got a multitude of options. In my opinion, your best choices are along Harbor Blvd from Manchester Ave. at the north, to Ramada Maingate at Disney Way at the south. However, Howard Johnson (HoJos) is well-loved by many and just north of Manchester on Harbor Blvd. There are also several often recommended hotels on both sides of Harbor Blvd as far south as Katella.
The crosswalk across Harbor into the parks is in the center of the block between Manchester and Disney Way, at IHOP. The closest hotels on either side are Best Western Plus Park Place and Park Vue Inn.
All this to say... If money isn't an object, you can't go wrong but to stay in the resort hotels. But there are so many good options that you certainly aren't limited.
I only go to Disneyland and visit friends when we go to the LA area. Nothing else appeals.

But there are many other options, other parks (Knott's Berry Farm, Universal Studios, Magic Mountain) beach options, Hollywood tourism options, historical (the missions, La Brea Tar Pits)... I suspect if you share what types of things interest your family, others can give good advice.
Also, make sure you visit the following thread. It's got links to all kinds of information, including a "Guide to DLR for WDW Vets".
http://www.disboards.com/showthread.php?t=1072276
Have fun!!!