I try my best to do atleast 2 or 3 days per week to go completely meatless and have been quite successful. I have found that getting adults to eat veggie dishes is to make the dish more flavourful until they get used to the taste. Using spices that compliment or enhance the flavour of the vegetable rather then trying to mask or make it taste like meat. Ethnic cuisines are always a good place to start on veggies -
http://www.vegrecipesofindia.com/. It also helps to make the dish look pretty.
I know some of the dislike of veggies comes from people having eaten veggies that were badly cooked as a kids and that still sticks with them as adults. Cooking veggies properly takes some time and practise since most have a much narrow margin of error then meats do.
I've done dinner where I invited heavy carnivores, fed them a complete veggie meal only for them to find out half way through that there was on meat on the table.
Anyway, here are some veggie dishes to get the ball rolling.
Roasted whole cauliflower seasoned with chilli powder, tumeric, asafoetida(an indian spice that tastes like onion, garlic and sulphur), lots of lovely olive oil and a heavy pinch of sea salt. I left it under the broiler for a abit to long so the top got slightly over charred then I would like for presentation purposes but the charred parts tasted the best.
Pani puri an indian street food/snack that all about textures and weird flavours. Fried dough that is then stuffed with boiled potatoes and chickpeas, filled with a super flavourful watery soup made from cumin and tamarind. topped off with cucumber, tomatoes, onions and coriander for some more texture and fresh flavour.
