In a medium bowl, whisk together all marinade ingredients. Set aside 3/4 cup marinade.
Pour remaining marinade over chicken pieces and stir to combine. Marinate, refrigerated, 2 hours.
In a large skillet over medium-high heat, add chicken and saute until cooked through. Work in batches as necessary.
Transfer chicken to large bowl, removing batches from skillet with a slotted spoon. Cool.
Divide evenly among one-quart size freezer bags. Divide reserved marinade evenly among chicken, shaking to distribute (1/2 tablespoon per serving).
Seal bag, pressing out excess air. Refrigerate.
Wrap pitas in foil (1 per serving).
Package cheese in snack bags (1/2 ounce per serving).
Place a package of chicken, a pita, and a package of cheese in each of one-gallon size freezer bags.
Seal bag, pressing out excess air. Freeze.
Yogurt-Dill Sauce: If substituting low-fat or non-fat yogurt for natural yogurt, strain overnight in refrigerator in a coffee filter-lined sieve.
Combine all ingredients in a mixing bowl or processor.
Beat or process until smooth. Divide evenly among small freezer containers.
Cover with a sheet of plastic wrap, pressing down to cling to food. Apply lid. Freeze.
Preheat oven to 350F. Warm foil-wrapped pitas in oven 10 minutes. Warm chicken in oven or microwave until heated through. Stir Yogurt-Dill Sauce and transform into Tzatziki by adding 1/2 large cucumber which has been peeled, seeded, finely diced or shredded, and drained.
Top pita rounds with chicken, Yogurt-Dill Sauce, and crumbled feta. Add fresh, sliced tomato if desired.