Some places we loved:
Akershus in Epcot (Norway) - this is a princess meal and a buffet. Great interaction w/ characters, unique food (cold buffet and then entree and dessert served at table). I am not sure how your son will react to a princess meal, however in my experience, the characters always make a special effort to include boys in everything that is going on. I guess his experience will depend on whether he cares at all about Disney Princesses!
La Cantina de San Angel (Mexico, Epcot). This is a counter service and it is, in a word, AMAZING!

We at lunch here one day. It was quickly served (as typical w/ CS places) and the food was so delicious. We ate right on their patio by the water. If you eat dinner here and time it just right, you can wind up sitting on that patio and watch Illuminations while you dine (this place is packed for Illuminations, so it's not a guarantee!). You have to go here, if not for a full meal, at least to grab an order of churros w/ milk caramel!
Chef Mickey's @ the Contemporary. Another fun character experience w/ a large buffet. We loved the characters here - They do a fun celebration song and dance (look up chef mickey's napkin waving, on
youtube, to see a video..it's really fun!). I have a 3 year old daughter, so we really enjoyed the character dining options. I found that it was a great way to get that character interaction, without having to spend a lot of park time waiting in line for autographs!
Contempo Cafe @ the Comteporary. While this was actually not one of my favorite spots, it's worth a mention just because it is so convenient to Magic Kingdom. We really needed a break from everything one evening, so we headed over and had flat breads for dinner. Truth be told, I was a little disappointed in my flat bread, however dh & dd both enjoyed their food..and as I said, it was great to just get out of the park for a little bit!
The foodcourt at Pop Century - crowded and kind of noisy at times, but any minor annoyances just fade away when you are devouring a Mickey waffle! I swear, some days I find myself just day dreaming about Mickey waffles - they are that good! I am pretty sure that you can find these at almost any restaurant serving breakfast, however we stayed at Pop, so naturally we ate breakfast there most often. I'm not sure what the food offerings are at POR, but if they include a place w/ Mickey waffles, then that is the place to be for breakfast! I bet your son will love them!
Columbia Harbour House in MK - another CS place. It was actually the first place we ate at on our vacation, and it did not disappoint. I had read many reviews of the lighthouse sandwich, so I was excited to try it. YUM!
If you go in and it seems crowded, look up - there is seating upstairs and it is a nice quiet, cool place to enjoy a meal.
Boma at AKL. YUMYUMYUM. We ate here after a day at AK. The food was really good, and very different than typical buffet food. The dessert offerings are just ridiculously good here! Worth a meal here for the desserts alone! We also enjoyed checking out the resort, as we were a tad early for our reservation time. Actually, we enjoyed it so much, that we are now heavily leaning toward renting points and staying AKV next year! The theming of the restaurant is beautiful as well.
Cape May Cafe @ Beach Club. We had breakfast here (our only table service breakfast), and it was impressive! I am not a huge breakfast person, because I just feel so weighed down and gross after eating a big breakfast, however I did enjoy the food here. All you can eat Mickey waffles? I'm in! The characters were fun here. We ended up meeting Minnie 3x on our 9 day trip, and it never got old. I just love how their outfits are themed along w/ whatever venue they are in. Disney certainly goes the extra mile! Along w/ the waffles, they also had a full yogurt bar w/ toppings, fresh fruit, a bagel bar, and several other hot breakfast options. Our server was quick to replenish our coffee and orange juice!
Wolfgang Puck Express @ DTD - we didn't have any places that we were dying to try in Hollywood Studios, so we decided to head off to DTD for dinner. I will say that getting there was practically a nightmare. We took a boat and a bus that seemed to stop a million times (probably really stopped 3-4x, lol). I think that there must be an easier way to have gotten to DTD, but anyway it is what it is. So we went to WPE and were famished. It's a counter service, however the meal is served at your table and on real plates vs paper. Kind of a nice little counter service upgrade! I got a pizza which was delicious. DD had pizza as well and DH had some type of pasta w/ chicken, if I remember correctly. DH & I both enjoyed the creme brulee for dessert and dd had frozen yogurt. They gave us SO MUCH FOOD. We really could have split my pizza as a full meal for 2 adults, however it was amazing so I ate most of it myself!

They have a nice patio area, where we sat to eat. Aside from our horrible travels to get there, this was one of my favorite meals - and all for a few counter service credits!
Rainforest Cafe @ DTD - they do not accept the meal plan, so we payed OOP for this one. To be honest, I dont' remember what I ate! The big draw here is the theming - every so often (I can't remember the time interval, but often enough to see it a few times while eating a meal) the animals 'come alive,' and start moving around and making their animal sounds. Our server was friendly and joked with us, everyone else dining near us seemed to be enjoying themselves too. I would eat here again if DD really wanted to, however it's not on my list of places that I must see again! All in all, the food is comparable to most chain family restaurants that we can eat in at home, however the theming makes it worth a meal there!
We ate at so many other places as well, but that is a sampling of some of my observations. Hope that helped you out a bit!