The combination of slightly better manners and a greater sense of adventure can make exploring new cuisines with tweens an actual pleasure.
Food festivals and fairs
We're not dealing with a cuisine here, but a concept -- one that has that useful interactivity thing going for it. Whether it has a single-cuisine focus like the annual Greek Food Festival of Dallas or encompasses a compendium like the Ninth Avenue International Food Festival in New York or the Taste of Hartford in Connecticut, food festivals tend to have a lot going on besides food. They create a sense of excitement that does wonders to put kids into an open-minded tasting mood. Even if you can only get them to try desserts, at least they'll associate the cuisine with something they like '- and next time, you can tempt them with the whole meal.
Argentine and Peruvian restaurants can go down pretty easily with kids because they can be relied on to feature a simple meat perfectly prepared (steak in the case of the former, roast chicken in the latter) and, if the waitstaff is also Latin, give your kids a chance to practice their Spanish lessons. If your kids like food prepared any way as long as it's grilled, check out a Brazilian or Argentine churrascaria, where roving servers spear up requested cuts (again and again and again). Their slicing and dicing and serving action is part of the entertainment, and it will go down big with kids.
Food on a stick
Okay, this isn't a cuisine per se, but it may open up a bunch of ethnic dining menus to you and your family. Whether it's satay (Indonesian or Thai) or souvlaki, grilled meat on skewers is both fun and nonthreatening; most kids will at least try it.