I'd second Ailefroide but it's not really a huge venue. Wonderful place to spend time though and the routes are also awseome fun.Chironico is a bigger area with tonnes of quality easier problems and I've not found it too hot in the summer; the tree cover and aspect helps a lot with that. Climb early and late, choose your problems carefully and you'll enjoy it. Dries fast and there's a brilliant guidebook too. Not far from St Gottardo which is also excellent in the summer. Not sure how accessible for a quick trip it is though as we've always been in the car and out in Switzerland for a long trip when we've visited these places.
It will be the blue covered one in Italian (with black and white pictures) I imagine?
