I think Guhagar beach-pawas-Ganpatipule-Ratnagiri will be an Idea plan for a family vacation in Konkan region.
Alternately you can also consider Alibag-Murud Janjira -Revdanda . Happy Travelling :)
Dear Nupur , there are lot of places you can cover , please let us know the place from you are travelling and for how many days so I can help.
In general I suggest Tarkarli with Guhaghar and GanpatiPule another group is Diveagar and surrounding and you can also do Dapoli and surrounding places such as Ladhghar beach etc.