You should always plan to visit pune during monsoon preferably July and August.There is nothing much within pune but places around pune are beautiful during monsoon.Those lush green mountains, amazing weather, chilled-out people and roaming around late nights without fear is what I love about Pune. You should hire a cab/ self-drive car(if you are comfortable driving in Ghats) for all three days, which is very convenient way. If you need any help with getting a cab in genuine rates, I can help you with that. You can plan your three days trip as:
Day1: Visit Mahabaleshwar , spend the night there. It will be all foggy and green. Must visit strawberry farms and have strawberry cream.
Day 2: Early morning leave for Panchgani and visit mapro garden and have sandwhiches there and if time permits visit Table land and leave for Korigad, it is a unexplored yet wonderful place to visit. If you need more details about Korigad, visit my story for korigad here. It is near famous Tiger’s point in lonavala.
At night, visit Tiger’s point and stay at a resort at Ambey valley.
Day3 : Must visit Matheran. Enjoy horse ride from parking lot to reach Matheran. It is sort of a Jungle trek. There are beautiful resorts to stay too.