For a first time visitor, I recommend 4 days at the parks. This will guarantee enough time to do what you want (most likely more than once) and get a feel for the resort.
Here are my top #10 tips for WDW vets
#1 tip. Get there EARLY! There are NO long lines in the first hour-hour and a half. Pick up a FP and enjoy some rides without lines
Use FastPass! (same kind of system as WDW)
Do not expect WDW size. DLR is so compact it is very easy to get around. Park hopping (or going to Downtown Disney) takes a grand total of 1 minute to cross the large plaza separating the two parks. It also makes walking the main transportation here, as opposed to buses.
I do not recommend staying onsite for a combination of two reasons. Cost and closeness. There are many many many offsite hotels with much cheaper prices. Also there are a handful of hotels that are closer to the parks than the
Disneyland or Paradise Pier Hotels. With cheaper prices and shorter/equal walk, I have always stayed offsite. While the quality may not be as good, it's just a place to sleep right? However if you intend to spend a lot of time at the pool or lobby or hanging around the hotel, you might be the kind of person who will want to shell out the dough, though I highly discourage it. More money for the parks!
Buy admission in advance definitely. Nothing like standing in another long line just to get into the park.
Eat breakfast at your hotel, or while waiting for the gates to open. Plus, breakfast in the park is mucho $.
Dont miss spectacular shows such as the Aladdin Musical at DCA and the nighttime shows Electrical Parade at DCA (both unique to DLR) and the nightly fireworks show and Fantasmic! at DL.
Do not eat lunch and dinner at normal hours to avoid food lines and take advantage of shorter ride lines
An alternative to carrying around all your stuff all day is to rent a locker. Theyre about $5 each and can hold a little more than a backpack size. Perfect for storing sweatshirts during the middle of the day (especially in October when it can get a bit chilly at night). Lockers are located about half way down Main Street to the right in a little corner at DL. At DCA they are just to the right of the entrance
Have fun!