I saw Laura Osnes as Julie Jordan in Carousel in Chicago, and I was actually struck by how much lightness and even humor she found in a role that usually has none. I would like to see what she could do with Eliza. I'm not sure she's my #1 choice, but I'm open to the idea.
I very much think That Thing You Do! should be expanded into a full musical by Adam Schleshinger (who wrote the title song and now writes for Crazy Ex-Girlfriend).