For starters, I would read this thread:
http://www.disboards.com/showthread.php?t=1162599
And no, I don't think one day is nearly enough. While DL only has two parks, vs. WDW's four, there is a lot packed into those two parks. And make sure you see the Aladdin show (at DCA) its the best live Disney show at either WDW or DL and that alone can take 90 minutes. Its a long show (around 45 minutes but well worth it) and you have to allow time to line up beforehand. Most of the WDW regulars who have gone to DL recently have really enjoyed their time. Its not WDW in that it doesn't have that huge, resort feel but its no shabby second cousin either! DL is the original and it has a huge amount to do and see. Of course one day is better than none, but I really can't stress enough you do at least two.
I recommend very much that you stay near
Disneyland, either at one of the onsite hotels (love them all but they are pricey, along the lines of a WDW deluxe) or one of the nice, clean, affordable motels on Harbor Blvd., that is walking distance to the parks. Some are as little as a two or three minute walk to the gates. It beats the hassle of L.A. traffic, parking and tramming if you stay further away.
By October the Nemo lines should be less, especially midweek. But bear in mind, that just like WDW, October is more popular than it used to be at DL. Fall breaks and just the rise in park attendance may make the line for Nemo still an hour or more during the day on a weekday, more on a weekend. Its just tough to say how Nemo will fare in the offseason since it just first opened. It doesn't have fastpass and is slow loader which is why the lines are so long. Disneyland draws way more of a local crowd than WDW and they all come on the weekends, so any weekend any time of year at Disneyland is going to be very crowded. But you need a weekend day since thats when they show the fireworks offseason at DL. They don't show them during the weeknights for the most part. And Remember is a great, not to be missed fireworks display. Starts out like Wishes then quickly branches off into something much different. Don't miss it! I also love the parade at Disneyland. So as you can see there is alot to do and even the rides that have WDW counterparts (such as Pirates) are worth doing. Very much so since some of them (Pirates and Space Mountain in particular) are much better. And DL's Fantasyland has several things (Mr. Toad, Matterhorn, Nemo, Alice in Wonderland, Pinnochio, Storybookland Canal Boats, Casey Jr. Circus Train) that WDW's Fantasyland doesn't have.
As far as meals, the Blue Bayou is a lot of fun (very similar to San Angel Inn since its riverside dining), its right inside the POTC ride. Its pricey and you need a priority seating. You can make that by calling: 714-781-3463 up to sixty days out. There are also some very fun character meals in the parks and in the onsite hotels. I like Goofy's Kitchen the best but they are all fun. So I would recommend one of those. DTD is also right there next to the parks and has some good dining and shopping options.
I would try to do a weekend day and a weekday. If you get a two or three day parkhopper, you can always spread those days out a bit. I love San Diego. But again, think if you do San Diego, you should stay down there to avoid the traffic which means a split stay. We did that in June and I was so glad we did. That way we could concentrate on San Diego and Disneyland separately since they both have so much to offer.
Good luck, have fun planning!
