I've done a cherry dubbel several times. The last time I used around 12lbs of cherries for a 5 gallon batch. I prefer to use mostly tart cherries.
Bottled/Kegged/Conditioning: Orfy's Boddington's clone, Orfy's Old Speckled Hen clone, SN Celebration clone
On Deck: Gumballhead clone, German Pilsner
Drinking: Old Ale, Bourbon Barrel Wee Heavy, Bourbon Barrel RIS