This is the hard thing...everyone has their opinions...many vary...and there really is no right or wrong.
As for character meals...
I think everyone needs to go to Chef Mickey's at least once. If not Chef Mickey's, at least a meal with Mickey..Garden Grill would probably be my other choice b/c of unique setting, food quality, service, and character interaction.
I also think either CRT or Crystal Palace for a pre-park opening meal is a must.
Beyond that...
While I have decided that the flatbreads and sushi are the most consistently reliable items on the Cali Grill menu, I think a meal up there timed with Wishes is a must for everyone.
I also think...
Special experience dinners/meals are a must. Not a ton, but at least one...whether it's 'Ohana dinner, WCC, 50s PT, Sanaa or Sci Fi...something that feels more unique to WDW.
Finally...
I think BOG and CRT, setting-wise, are worth a visit. Food can be hit or miss, but both have a nice wow factor.
A side note...while there is lots of other great dining, especially signature dining, but outside of V&A or Narcoosee's timed with Wishes (still prefer Cali Grill), the rest don't have as much of a Disney vibe.