To be honest, if they're not interested in it you're going to have a hard time trying to get them to be. My kids (12, 9, 9) don't have a ton of interest in it either and never have. They don't hate it, there are some odds and ends that they like, but it's far from the highlight of their trip. I'm not saying to just skip it, certainly not. I just think you'd find it tough sledding to try to get them interested in something like the World Showcase if they're not pumped about it now. It's not really a kid centric place, at least not as much as the rest of the parks are, and that's OK. We tried the Agent P thing too, but they had no interest in it, so we didn't force it. We don't spend a lot of time in the World Showcase ourselves, but when we do go here's what we tell the kids...first, keep an open mind, you never know what you may like. Second, if you don't like it, that's OK, but be patient and deal with it until we're done. They have pleasantly surprised themselves a few times.
My best advice is to talk about some of the things in there they may enjoy (FEA, boat ride in Mexico, some of the shops), so they at least have a few things to look forward to. Other than that, don't try to force excitement, rather just get them to understand it's part of WDW, and a part you and DH enjoy.