And if you don't have time or the desire to do Knott's, you still might want to swing by as part of a general self-tour of the Anaheim/OC area and poke into a shop or two and/or the Independence Hall, which are all outside the part of the park you actually have to pay admission for.
But Tony Roma's is conveniently located right across the street from Disneyland. It's a big U.S. chain restaurant (you'll find one at CityWalk at Universal Studios as well), but they're really good. Share an onion loaf. My husband likes his beef ribs there dry, with only the sauce they're cooked in, which makes it like Prime Rib on a Stick.
Oh, and if you're going to Universal, there's also the Saddle Ranch Chop House, right next to the park entrance. I don't think I've ever had their ribs, though, so I can't tell you how they are.
And as for Disneyland, don't define a "successful" day by how many rides you went on. Some people are so concerned with not missing a single ride that they completely miss the atmosphere of the park. Take time to slow down and check out the details, and just BE in Disneyland.
ETA: Darn it, now you've got me craving ribs. Guess I know what I'll be having for lunch.
ETA ETA: Newport Rib Company on Harbor Blvd. in Costa Mesa is also good, but it's about eight miles south of Disneyland.