Simply Thai is one of my favorite veg-friendly restaurants. Almost any dish can be made with tofu, vegetables, or TVP instead of a meat option. You also have options for the level of spice that you want (from 0-5, 0 being no spice and 5 being "Thai spicy") to further tailor your dish.
I've tried a number of the items on the menu. With the exception of the sushi (which was good but not outstanding), I would definitely order them again.
Cons: Slow service