In a heavy saucepan, cover lentils with water by 2 inches and simmer until just tender but not falling apart, about 15 minutes. Drain lentils well in a sieve. Rinse lentils under cold running water to stop cooking and drain well. In a bowl, toss lentils with 2 tbsp vinegar and salt and pepper to taste. In a skillet, cook bacon over moderate heat until crisp and with tongs transfer to paper towels to drain. Crumble bacon.
In a saucepan, heat 2 tbsp oil over moderate heat until hot but not smoking and cook shallot, stirring, until golden brown. Stir in water, cherries, sugar, and remaining 5 tbsp vinegar and simmer, stirring occasionally, until liquid is reduce by half (about 10 minutes). Reduce heat to low and whisk in remaining 2 tbsp oil in a slow stream until emulsified. Season vinaigrette with salt and pepper.
Add half of vinaigrette to lentils and toss well. In another bowl, toss spinach with half of lentil mixture, half of bacon, half of cheese, remaining vinaigrette, and salt and pepper to taste. Divide remaining lentil mixture among 6 plates and top with spinach mixture. Sprinkle salads with remaining bacon and cheese.