Here are some must things to do in Lonavala
Camp at Aundholi
Hike to Tikona fort
Walk at Rosewood park
Ride at Lonavala lake
Explore Karla caves
Try to peep from Tigers leap, dukes nose and Amby valley to have a view of picturesque places
There are many beautiful places in Lonavala
If you want to go for camping try Pawana Lake Camping.
You can also visit Bhushi Dam. There is this Duke's Resort which has many adventure activities.And you will surely find many waterfalls on your way to Lonavala.
I am not sure if you are mobile or not but if you have vehicle at your disposal, you can experience night tour. Go towards Tiger point at night and en route you will get a bridge before bhushi dam. eating maggi at night when crowd has gone hiome, is amazing experience. one or two places are open whole night. next surreal exp will be Karla caves. they are buddhist caves built by traveling buddhists
Last one, do visit wax muesuem. they have done good job.