I have tart cherries in a wheat right now. The airlock still bubbles every now in again after 12 days at 70 degrees.
I'm thinking about brewing a quad in the fall. I was thinking sweet cherries. Are you planning on aging at all, Jim? Jon mentioned Three Philosophers... I recently found a four pack of 2011 Three Philisophers stashed in the back of the "beer cellar." It tasted like a little slice of heaven. I wouldn't expect you, or me to age a beer for 3-4 years before drinking it, but maybe try "losing" a few bottles somewhere in the house for awhile if it turns out good.