I am mostly vegetarian and have been for much of my life. I do eat fish, the occasional egg, a little poultry and rarely other meat. It's not an ethical or political choice, but a health choice because I have trouble digesting animal protein and dairy, and I have a number of food intolerances. So, I've been eating mostly raw for a very long time.
Brown rice is another good choice over white rice, and I also like the nutty flavor of wild and other "exotic" rices (ever tried mahogany?). Plus, I absolutely love couscous Tunisian style (more savory than Moroccan).
Buy organic what you consume the most, otherwise, it may just become an expensive waste of money.
I have been advised to avoid nuts and seeds until after my colonoscopy in August (my doctor suspects diverticulitis, which can be caused by nuts, seeds, popcorn and other such rough foods). Otherwise, I always included pecans, almonds and walnuts (think PAW) in my daily regimen, and I love air-popped popcorn!
Raw in my house also includes certain fish, although this is not necessarily part of the "raw diet." We regularly eat sashimi of tuna or Pacific salmon. No cooking there, either. (Note: sushi means rice, sashimi is the raw fish; not all sushi contains raw fish; I don't particularly care for sushi and won't eat the rice.)
I like to make my own yogurt and yogurt "cheese," having learned how while at university overseas. In the Middle East, it's called "labban," and it's a wonderful substitute for sour cream in sauce, or for making Greek tzadziki (yogurt dill sauce) that is wonderful on raw veggies. Coincidentally, I was talking to my coworker about making yogurt; haven't made some in a while.
Stevia is a natural sweetener, so feel free to go with it. I also buy honey straws to use in my tea.
Sprouted breads are wonderful, they just don't last very long in the fridge and often taste better toasted. I particularly like a sprouted sourdough that is very hard to find, but is sometimes carried at our local chain grocer's.
Tofu is a processed food. However, it is soy. Your kids might like playing with their food - steamed edamame pods are a blast for kids to pop.
Carob is a good substitute for cacao or chocolate, and it tastes good. But, you really don't have to go that far. Bittersweet or dark chocolate is fine.
The problem with buying certain things in bulk is that you might not use them up before they go bad. Nuts and seeds turn quickly.
During the summer, we do a lot of outdoor grilling and eat a lot of fresh - and raw - fruits and veggies. Personally, I have to remember to balance fruit with veggies, as I tend to eat more fruit. For protein, besides fish and the occasional bit of animal (about 1-2 ounces), I go for edamame.
I don't remember having trouble getting my kids to eat raw, I guess because it had always been a part of our regimen.
Good luck with your 21-day experiment! Who knows, maybe the grandparents will "come around" - if it looks and tastes good.