If you are taking your own car, no need to hire a car or driver to visit places around. I suggest to avoid staying in Murree, spend half a day in Murree and move on to Nathiagali,. Murree is expensive, crowded, nothing much to see and do there. Better stay in Nathiagali, you can visit Ayubia, do some hiking. Its peaceful and more beautiful. Hotels are cheap as as well compared with Murree.