Lilo and Stitch is considered to be Disneys last major 2D hit...and in my opinion, their last overall hit. It spawned mutliple sequels, a TV cartoon and multiple toy lines. It was completely original compared to everything else that they had been attempting to churn out.
I haven't seen Bolt, but I'm not sure that I would consider it a major hit for Disney. It did well enough, but didn't have the strong staying power that something like Lilo and Stitch did. It just sorta dropped off of the radar after a couple weeks. (Interesting though that it was originally Chris Sanders project...wonder if it would've had more staying power had they not removed him from the project and reworked the entire thing??)
Also keep in mind that Lion King seemed to be the pinnacle of Disney animation. Everything after Lion King had a drop in quality, both story and artistically...with the exception of Pocahontas, it's artistic direction was a different step for Disney at that point and it was a beautiful movie, it just didn't measure up to the under dog story that Lion King gave audiences. Disney was never able to reproduce the magic that came from the Lion King and they put a lot of effort into doing so. Unfortunately for them, Pixar at the time was tackling completely original stories that were fun and memorable. That's why the Pixar movies became so popular, they weren't reruns of stories that everyone had already heard (Pocahontas, Hunchback, Treasure Planet, Hercules....yawn....made years ago by someone else).
So...I personally think that Lilo and Stitch would be Disneys last successful film. It succeeded where all there other films were failing and it was a fun movie.