Our family of three veggies and one meat-eater are going in just 31 days

It will be our fourth trip in about 5 years. Let me just first say that I LOVE BOMA! It is really the best veggie dining I have found in WDW. On my first trip there, the chef personally walked me through the line and explained the ingredients in all the dishes. He also made an incredible couscous dish just for me and my daughters. More veggie options there than I could even eat. This trip, we are trying Tusker House buffet for lunch, instead of Boma, hoping the food is similar and just as tasty!
We also have ADRs at 50's this trip - never been before, but the vegetarian ratatouille stuffed pepper on the menu looks great. I'll let you know how it is!
Some of my other favorite veggie places:
In MK: Columbia Harbour House can't be beat for a veggie CS. They have veggie chili and a veggie hummus sandwich. Cosmic Ray's has a veggie burger, as does the Plaza. Liberty Tree has a veggie / grains dish that is average.
In AK: Tusker House is really the only good option - altho you can get a veggie burger at Restaurantosaurus. I have also read on disboards that Flame Tree BBQ has a large and tasty fruit & yogurt plate. Pizzafari has bread sticks and marinara dipping sauce.
MGM: We've eaten at Mama Melrose a few times and have really enjoyed it. They have a vegetarian minestrone that 's great, and their salads and flabreads are yummy! You can even request no cheese if you prefer.
Ohana at Poly - Their veggie choices are really limited, although the chef did come out to greet me and prepared a special tofu dish.
Le Cellier - could make a meal of those pretzel breadsticks

, but my entree was decent - a portobello dish I think

, but I do remember that they were nice and accomodating.
We are also trying Chef's de France this trip, since I have read that it is one of the better / more accomodating veggie choices in Epcot.
My bottom line - ALWAYS tell your TS server first thing, and in my experience, they are usually very nice about answering questions & offering different options. Hope I've been helpful!