IMO, the hotter weather lends itself to the belgian/saison yeasts or the white labs east coast / california / california V yeasts. Right now I have a belgian dubbel and a "misfit" beer going (had a random jug of malt extract and a bunch of special b laying around).
I could easily add sour cherries to either of them, the trick is to figure out how much, and how your going to do it. My advice is to keep it simple, 1 lb per gallon should give a noticeable, but not overpowering tart flavor to the beer, but 2 lb per gallon may be waay waaay too sour. I'd say keep it closer to 1#/gal if this is your first time. When I add fruit, I always rack the beer to secondary, see how much more volume I want to meet the desired level of beer, put that much water in a pot with the fruit (I lightly crush the fruit usually but nothing says that you have to) bring it to about 170 degrees for 2-3 minutes, chill then pitch onto the racked beer, put the stopper back into the carboy and give a good swirl, let it sit for about 2 weeks.
Conversely a few months from now, when the mulberry tree in my yard really starts to drop some fruit on me, I'm going to make a mulberry lambic, for blending with belgian style strong beers in the style of Ommegang Three Philosophers in the future.