With a vegetable peeler, pare only golden part of peel from 1 grapefruit.
Cut peel into very thin, long slivers.
With a knife, cut and discard remaining peel and white membrane from each grapefruit.
Hold fruit over a bowl and cut parallel to membrane to release segments into bowl.
Squeeze juice from membrane into bowl; discard membrane.
Drain off juice and reserve.
To fruit, add cherries, 1/2 cup liqueur, and sugar to taste.
If made ahead, cover and chill up until next day.
In a 1 1/2 to 2-quart pan, combine slivered peel and 1 cup water.
Bring to a boil over high heat; drain.
To the peel, add reserved juice, remaining sugar, and honey.
Boil, uncovered, over high heat; stir often to prevent scorching.
Cook until the peel is translu cent and the syrup is reduced to about 2 tablespoons.
Stir in remaining liqueur; remove from heat.
If made ahead, cover and let stand up until next day.
Ladle fruit and juices into individual bowls and top equally with peel and syrup.