There's a range of good behaviors that I classify as "table manners." These range from pretty basic (don't throw food) to general politeness (use your fork and spoon, napkin on lap) to moderately obscure and/or localized etiquette (start with the salad fork, which is on the left).
For general purposes, we only focus on the first couple categories at home. However, there are going to eventually be situations where I'd like them to know how to be on their "best behavior" -- and indeed, they'll likely feel embarrassed and uncomfortable if they don't know what is expected. My mother always phrased it as we should be "ready to be invited to dinner at the White House"... but I have in mind more events like wedding receptions, eating out with work colleagues, or going on dates to fancy restaurants.
What are some ideas for incorporating the extra-polite aspects of table manners into their education at home? I don't want to make every meal into a high-pressure fancy occasion (for one thing, I don't think I have enough forks), and I also want to keep it fairly light and fun. I remember my little brother getting yelled at by our grandfather once for dropping his napkin: this didn't teach us how to deal with napkins, just that Grandpa was somebody to be afraid of.
I don't expect this to involve kids under 7, unless somebody has a brilliant suggestion for how a toddler can learn the difference between soup and dessert spoons. I do want to start before they're teenagers, though.