There is WDW without the dining plan, and then there is WDW WITH the dining plan; they are very different options.
We have always done at least one character meal without it but it was always breakfast as it is the cheaper option and you do not interrupt the day. However with the dining plan the whole world literally opens up to you.
Recommended character meals in order: -
- 1900 Park Fare, Grand Floridian Resort (both breakfast AND dinner)
- Cape May Cafe, Beach Club Resort (both breakfast and dinner)
- Chef Mickey's, Contemporary Resort
- Crystal Palace, Magic Kingdom
- Tusker House, Animal Kingdom (book the earliest time on a non-early entry day to get access before everyone else)
Recommended park restaurants in order as much as possible: -
- Tutto Italia Restaurante, Epcot Italy
- Rose & Crown Dining Room, Epcot UK (dinner for Illuminations, also good value without dining plan)
- Yak & Yeti, Animal Kingdom
- Biergarten, Epcot Germany (free show every hour or so, also great value without dining plan)
- Garden Grill, Epcot Land Pavilion (good value without dining plan)
- Les Chef de France, Epcot France
- Coral Reef, Epcot Seas Pavilion
Recommended non-park restaurants in order: -
- Boma, Animal Kingdom Lodge (both breakfast and dinner)
- The Wave, Contemporary Resort
- Planet Hollywood, Downtown Disney
Recommended quick service: -
- Sunshine Seasons, Epcot Land pavilion (so much choice, good with or without dining plan)
- Cosmic Rays, Magic Kingdom
- Flame Tree BBQ, Animal Kingdom
- Fairfax Fare, Hollywood Studios
- Old Port Royale, Caribbean Beach Resort (get the smoothie as a drink on dining plan)
- Mara, Animal Kingdom Lodge
- Wolfgang Puck's Express, Downtown Disney (queue was ridiculous so I never tried it personally)
As for avoid, the places not listed above were ruled out for one reason or another, and you can really only do a certain number of places during your stay.