Brush the watermelon with oil. Season with salt and pepper. Grill the watermelon wedges for 1 to 2 minutes on each side.
In a medium bowl, toss the greens with the vinegar. Season with salt and pepper to taste. Set aside.
To assemble the salads, sprinkle each grilled watermelon wedge with feta or goat cheese. Top with the greens. Sprinkle a little more cheese on top, if you'd like.
Notes
If you're counting WW Points be sure to use reduced fat feta in the salad.