Willibug, It's funny, I also feel rejected when ds or dh don't like my food. It doesn't happen often, tho. I have been known to get a little testy when dh adds pepper to my spaghetti sauce. Anyway, I was raised as a grazer. My mom always had healthy snacks, we never sat down to meals. I could probably count those occasions on one hand. Now, with ds, we always sit down for our meals, dinner always we are all three (now 4 with the baby) together, no tv, just us eating. When ds is done, he gets down and dh and I get a chance to visit. Ds is quite an eater and I rarely have to worry that he is full and won't eat supper. If he says he is hungry while I am cooking, I tell him to wait, if he says he can't, I let him have a couple of crackers or something so he is not starving. My feeling is that your kids are probably getting a good diet, and if your arrangement works, fine. For me tho, I missed not sitting down for dinner with my parents, and now that I think back, the marriage was not so good anyway, so maybe sitting at the dinner table is for me reassuring that our family is OK. (I'm talking about my issues here)
Anyway, I have a friend that lets her kids always pick out one veggie each week at the store. That might work for getting them to try new things. Also, bringing them to a farm stand might get their curiosity up. I have no problems getting ds to try new things. I always ask him to take one bite, if he thinks it is gross, he doesn't have to try it again, but I tell him that I'm proud of him for trying something new, and remind him that he used to not like pancakes, which are now his favorite. Also, we tend to quote Dr Suess a lot "I do, I like green eggs and ham, thank you thank you sam I am"
We also make a big deal out of breakfast on Sundays. Pancakes, of course. Now that I am really thinking about this, I sure do idealize the happy family eating at a table together.
At three and six, I would also get them involved in the cooking. I bought ds a pumpkin carving kinfe that is also sold as a kids safe knife and let him cut things. He helps add ingredients when I bake, he mixes, etc. Makes a huge mess, but he always eats what he makes.