Hi MaidMarion!! Welcome to the DIS!
If you like the amount of food you can eat at a buffet, without all the work of actually fixing your own plates

then try the all-you-can-eat family style restaurants. The Garden grill at Epcot, Liberty Tree Tavern at MK (one of my favs), and 'Ohana at the Poly all offer their meal in this manner. It is all you can eat, but is brought to your table in serving dishes, and then you eat what you want from the serving dishes and tell the server what you want more of.
At the Garden Grill you will be able to see Mickey, Chip and Dale and be served rotisserie chicken, fish, steak, potatoes, vegetables, salad and dessert priced at $21.99 pp.
At LTT you can see Minnie, Pluto, Donald, Daisy, and Meeko (Goofy, Chip and Dale used to be there, but have recently moved to the new show at the Diamond Horseshoe) and dinner includes ham, turkey, flank steak, vegetables, salads and more priced at $20.99 pp.
'Ohana is not a character meal. Dinner there includes Stir Fried Vegetables, Salad with Honey Lime Dressing, Shrimp & Vegetable, Wontons, Honey Coriander Chicken Wings, Vegetarian, Stir Fried Rice, Skewers Prepared over oak fire: Grilled Tiger Shrimp , Marinated Sirloin Steak, Mesquite Seasoned, Turkey Breast, Barbecue Pork Loin for a price of $23.99 pp.
If you are looking for filling meals at a more budget minded price, you should definitely make use of the AK "meal plus" deal (if they are still running it when you go). With this you get an entree plus a drink of your choice at Restaurantsaurus, Pizzafari, Flame Tree, or Tusker House, plus you also get a voucher for a box of popcorn or an ice cream as well as a voucher for another bottled drink all for $11. You can get the most for your money and appetite if you go to Flame Tree or Tusker house!!
Other places where you can get larger portions for a good deal include:
Counter Service:
Cantina de San Angel (Epcot)
Sunshine Season Food Fair (Epcot)
Cosmic Ray's Starlight Cafe (MK) - esp. the "Family Meal"
El Pirata y el Perico (MK)
Sit Down:
Beaches and Cream (Beach Club)
Wispering Canyon (WL)
Trail's End (Fort Wilderness) - buffet