You could check on the following
Mahabaleshwar Panchgani
Igatpuri
Matheran
Malshej ghat
Ganapathiphule
Lonavala and Khandala
Amboli
Karjat
Rajmachi
Lohadgad. It is monsoon time in Maharashtra during month of June, where you get to see lovely greenery with drops of rain producing cool weather.
June is a start of monsoon. The places which are must visit in rainy weather/season near Mumbai are as follows
1. Matheran
2. Devkund Waterfall
3. Lohagad-Visapur (Trek) (Level:Easy)
4. Malshej Ghat.
Lonavala: a misty humid wet Destination for perfect leisure vacation
Matheran: hilly excruciation together with a nice horse ride
Panchgani: for soothing eyes experiences with a flaura and fauna
Mahabaleshwar, Pachmarhi, khandala and list stills go on
I would highly recommend that you visit Puerto Rico, it's heaven on earth. If you doubt my words, read this: https://tripbirdie.com/puerto-rico-all-inclusive-family-resorts/ Have you read it? Don't doubt it now. This place falls in love at first sight. So, in answer to your question, I will say with confidence - Puerto Rico.