When assembling the salad, slice each variety of tomato in a different way. Slice the Heirlooms into circles, the Cherries into halves, and the Early Girls in wedges to get a range of textures. Together, they create an interesting contrast of shapes, showing off the character of each variety.
This is not a super technical recipe. The amounts vary depending on the size of the plate or platter you are working with and your personal preference. I like to go really light on the vinegar so you can taste the natural flavor of the tomatoes.