First of all salam, and hope you find this in best of your health . dear sir @HanifBhatti your suggestion gratefully accepted 
as always . i would like to add up and share my experience with the above as i came back two weeks ago from khunjerab.
- I am planning a return trip in 05 days (isd-khunjrb-isb)...I am thinking of reaching Khunjerab with two night stays and on return also 2 night
Ans:--Day 1-
isb-Atd(leave around 6 in morning)
Atd-Balakot(approx 2.5 hous)
Balakot-Naran-Chilas(Dont stay long for sight seeing as they close babusar top for crossing at 5 pm no one can cross after that due to v steep descend). there are few good staying places like mr bhatti said., stay at chilas (although i reached chilas at around 5 pm i didnt stay and went directly towards gilgit, it took me 3.5 hours from chilas, roaad was rough for say about 1 hr but then it was a motorway quality(though width is less))
Day-2 Chilas-Gilgit(leave chilas at 6 am), you will reach gilgit around 9, have a breakfast over there. (there isnt anything to see in gilgit now a days the market is also not having the trade material etc) . leave gilgit at around 11 and head to hunza(stay for tea at rakaposhi view point that come on main road ). (Vital place to visist is Baltit- Altit fort, rest is natural beauty ) . have an apricot juice at the foot steps of baltit fort. and leave for ahead. at 15 - 20 min distance stop at attabad lake and enjoy tunnels and lake, after that leave towards the gojal and passu(the mighty passu cones). i would suggest you that you stay for the camping at Gojal (Passu Cone View is there) ,they offer neat an tidy family camps (cooking facility also available etc and restrooms also). have a bbq at night and see the star trails etc.
Day 3- Camping-Khunjerab Leave for khunjerab at around 7 in the morning . you will reach Khunjerab via gojal,sost,Khunjerab national park in around 3 -3.5 hours. enjoy the border sight seeing (it takes not more than 1 hour at the top as there is limited oxygen but its easily manageable ). Leave back around 1 pm and visit sost bazaar (although too few chinese things yet a good adventure ) . From here you can iether rush back to gilgit(it takes 4-5 hours , depending upon speed) or you can stay at passu camping again(i would suggest you go back to gilgit).
Day 4- Gilgit - Roam around gilgit etc, have a rest , or You can rush back till chilas again if you leave at around 2-3 pm. have a rest at chilas.
Day 5- Drive from chilas to isb early morning (via babusar if it is open).
MOreover there are few things that i had considere in my self opinion.
1-you can have a one day stay at naran (might be the first day). leave early morning for gilgit.do family rafting 10 15 min ahead of naran as its a worth experiencing activity.. if you do this you will go to gilgit irectly the same day as you will not stay at chilas
2.Most Economical with family even is the camping as the camping place's location is comparitively near to khunjerab as compared to gilgit or hunza. and its the best way to enjoy the nature.
3.Keep warm cloths with you speially for khunjerab as it may recieve snowfall at anytime of the year
4.Keep Fuel Tank at top up. and also keep some extra as fuel stations are at very very far distances.
5.When you reach khunjearb or any other place, dont turn off the engine at once, make it idle for 2 - 3 minutes. and then turn off. efi or electric fuel pump vehicles have no probles at khnjerab as their chances of getting low pressure are very less. conventional pump vehicles may not get fuel from fuel pump due to low air pressure.(its just a generic statement nothing much to worrry )
6.keep extra tyre in a working condition
7.when you reach top, dont try to exert hard. walk slowly and gradually as oxygen is less at 15- 16000 feet.
this was my experience , others may diifer. rest is an exploring activity and self affordability .
Best of luck for the trip and do share pics.
Regards
