With a vegetable peeler, cut 3 strips of peel (each 1/2 by 3 inches, orange part only) from 1 orange; cut 2 strips (each 1/2 by 3 inches, green part only) from 1 lime.
Place peel in a pitcher; bruise with a heavy spoon.
Squeeze oranges to make 2 cups juice. From 1 lime, cut 5 thin center slices; cut slices in half and reserve.
Squeeze remaining limes to make 1/4 cup juice.
Add orange juice, lime juice, and grape juice to pitcher; mix.
Serve, or cover and refrigerate until next day.
Offer citrus blend with sparkling water, reserved lime slices, and ice. For each serving, fill glass with ice, juice, and water, using about 2 parts juice to 1 part water; garnish with a lime slice.