Preheat your grill or grill pan over medium-high heat.
In a large bowl, combine the zucchini, red bell pepper, yellow bell pepper, and red onion. Drizzle with olive oil, then sprinkle with garlic powder, Italian seasoning, salt, and pepper. Toss until the vegetables are well coated.
Place the vegetables on the grill and cook for about 5-7 minutes, turning occasionally, until they are tender and have nice grill marks. Remove from the grill and let cool slightly.
Lay out the whole wheat tortillas on a clean surface. Spread about ¼ cup of hummus on each tortilla.
Evenly distribute the grilled vegetables over the hummus on each tortilla. Top with baby spinach and feta cheese if using.
Roll each tortilla tightly, tucking in the sides as you go to create a wrap.
Slice each wrap in half and serve immediately, or wrap in foil and refrigerate for up to 2 hours before serving.