Nag Panchami is a festival dedicated to serpents and is mostly celebrated in all parts of Maharashtra, West Bengal and many other, this festival comes in the month of July or August.
You could never come back disappointed if you visit the places in Panchgani- the land of the five hills. Just go there, enjoy and come back to endorse my view.
Shravan is a very auspicious month of Hindu's, in this month you can enjoy various festivals, the Shravan 2011 starts on 31st July and ends of 29th August.
Monsoon Festival of Saputara marks its start on July 30th and ends on 30th August, this is a month long festival for the first time in the only hill station of Gujarat.