So far, I have been able to eat at the TS in Mexico, Germany, Morocco, France, and Canada as well as the Garden Grill at the Land. My personal favorites were the Biergarten in Germany and Le Cellier in France. For families, I have to say I will always recommend the Biergarten. The reasons are several fold. One, it is a buffet but with some interesting options. Thus, you can dictate the pace of the meal rather than the server. It has some very fun entertainment offerings (the past couple times I went, almost all of the kids in the place were out dancing on the dance floor). Plus, if you have any inclination for beer - this should be your stop. They celebrate it throughout the show.
One point about choosing a viewing spot for Illuminations, try not to let the country dictate your spot but rather where the wind is blowing. If you have the ability (sometimes with large crowds or small children, this is not an option), try your hardest to be on the side of the lagoon where the wind is blowing away from you. I have seen Illuminations more times than I can count and I have NEVER had very good luck when in the UK, France. The wind always seems to be blowing that direction and makes the show somewhat unbearable... nothing like trying to enjoy a fireworks show while choking on a slowmoving cloud of smoke. My best luck has always come in Mexico, Norway/China, or Germany. The most wide open viewing areas free of trees/obstructions/etc has to be the stretch of path from Mexico to China. So my suggestion is to eat wherever you are going to eat and then go somewhere else to find a viewing spot. Finally, there is a viewing area at the very beginning of the world showcase which the show was meant to be viewed from. It also allows for a somewhat quick getaway as it is the closest viewing area to the exit. However, it is very popular and tends to fill up quickly (it also has a tendency to be closed off for banquets/conventions/private parties).
Hope this helps a little.