Let's see... generally there's no place in WDW you can just walk up and be seated unless you have ADRs. Even with them, there's sometimes a lengthy wait (we waited almost 40 minutes to get into Chefs de France, despite having a reservation

). The only walk in and get a seat and eat places are counter service. Especially in summer, you definitely without question need to make reservations. Most of the restaurants aren't exactly moderately priced; it's easy to drop $60 on not much food at all. But some are much higher than others. I'll list all the table service places I've been to and what I thought of them, and hopefully that'll help get you started. I'm sure others will add to this as well.
Magic Kingdom:
I have yet to eat a TS meal there
Epcot:
Chefs de France, France-- I always order the French onion soup and usually a dessert. I'm a light eater, so that's enough for me. Soup is around $5.95. Entrees go up into the $20s, if memory serves. My dad loves their lobster bisque as well. It's a fine place for children; not an adult only feel at all
L'Orginale Alfredo di Roma (or some such arrangement of words; I never can remember the exact name)-- my mom and I had the fettucine alfredo for around $15.50, and my dad had spaghetti and meatballs for maybe $14. All were delicious, particularly the alfredo. Another place that seemed child friendly to me
MGM:
50s Prime Time-- only had dessert here, but the atmosphere is great for children and adults, provided you get a good waiter/waitress. even if not though, it's still fun.
Sci-Fi Dine In-- atmosphere is great again, but I hated the food (over cooked, burnt, tough, you name it) and it was incredibly expensive. That meal almost cost as much as breakfast at Chef Mickey's!
Hollywood Brown Derby-- more upscale, but still child friendly, IMO. Yummy Cobb Salad (around $15 when chicken was added) and delicious Grapefruit Cake. My dad loved the coconut shrimp (around $7 for two huge shrimps plus some fruit and noodles, I believe).
Animal Kingdom:
Rainforest Cafe-- a lot of people hate RFC, but we love them. The Passport to Paradise pizza is great, as is the desserts. And oddly enough, it seems to be the one restaurant in WDW that sells sweet tea...
Contemporary Resort:
Chef Mickey's Breakfast buffet-- not cheap (around $18.99 per adult), but worth it. Some of the best memories of my traveling life. Food was wonderful as well. Go around 11 or so, and you can use it as a sub for lunch (even though it's breakfast food)
California Grill-- very upscale (in my opinion anyway), but children were still welcomed. Also very expensive. We each only got a flatbread pizza because we weren't too hungry (very yummy though) and tea, and it came out to over $40. Those pizzas were mainly the cheapest thing on the menu, so needless to say it's not cheap. We ordered them though not because of price but reputation; and sure enough, they were amazing.
Anyhow, hope this somewhat helps, even if just to give you some ideas. I would rank the restaurants as follows:
1. Chef Mickey's (I'm 23 and I still

it!

)
2. Alfredo's
3. Hollywood Brown Derby
4. California Grill
5. Chefs de France
6. Rainforest Cafe
7. Prime Time
8. Sci-Fi
Only one I will never return to is Sci-Fi. I'd suggest you decide something quickly because many places may already be full. I hope y'all have a great trip!
