In Islamabad you can Visit
Faisal Mosque
Shahdara Picnic Point.
Saidpur Village (F-6/3 Margalla Road)
Wildlife View point (Jungle Point) at pir sohawa road. you can see wild life from jungle.. e.g boars. fox, jackal etc (depend on luck) best time in my view is sunset...(not much sure)
Damen-Koh
Monal Resturant --- You can eat a good meal and also do a trekking from the Garani Peak... (trek start from near resturant)
Pir Sohawa - Enjoy the ride of Margalla Road... View from here the Highest Point of Margallas (Charani Tower Peak)
Shakar Parian - Pakistan Monument
Bari Imam
F-9 Park
Rawal Dam and Lake View Park
Chattar Park
Ayub Park Rawalpindi
Can do some trekking.. Trail 3 with start from Sector F-6/3, Margalla Road. Easily done with family. Very safe trek..
But due hot, you can visit in evening...
For nature lovers, hikers, Islamabad is a paradise. Do feel the air passing through the pines... enjoy fresh air on margallas.