first of all 4 days is too short if you really enjoy the places then increase your day...
second if you see the good and scenic view then travel end of june or start july....because travel via kaghan naran babusar is more scenic and comfortable due to good road condition but babusar top is open in june so plan your date according that...in may you can travel thorough KKH via dasu besham but it is very hectic and long route and road is also bad so try to travel end of june or july start....
booked a hi roof van which is suitable for family and comfortable also booked on daily basis rent and fuel is yours....
if you have a short day then give you plan....
1 thing note also start travel early and reached destination in light before maghrib or at the time of maghrib do not travel in dark in mountain area...
Day 1 : start travel at 4/5 am sharp to avoid rush in abbottabad mansehra....start travel at 4 am and go via haripur then abbottabad then mansehra you 1st stop at mansehra for breakfast after that travel to balakot after balakot most beautifull scenic view start and continue travel till naran with some little stop for relaxing and photographic you can reached naran maximum 6 hrs...dont stop at naran bazar it no need travel continue and stop after naran where river kunhar is near to main road stop on river its a beautiful place then travel continue till lulusar lake which is located at main road very beautiful place to stay....then continue travel till jalkhad and then babusar top after kaghan and naran there is too much cold weather and on babusar top very cold breez so dont forget warm cloth like jacket gloves cap babusar top is 13700 feet high but its a very beautiful place and very scenic...try hot pakora and boil egg and tea its very tasty in cold weather maximum stay on babusar is 1 hrs then travel continue there is steep slop and then after babusar the place is chillas 13700 feet to 800 feet and weather totally changed weather is same like isb and rwp in chillas but dont stay at chillas travel continue till rai kot and jaglot after rai kot 2 stop 1 is junction point of 3 mountains range and 1 is nanga parbat view then continue travel til gilgit and 1st night stay at gilgit...if you start travel at 4am then hopefully you reached gigit at 7pm....booked hotel 1 thing first check the hotel rooms and service available if you are 6 then booked suit room and take some mattress and live in 1 room its better....hotel rates in gilgit very reasonable and good hotel also in very reasonable price so booked at the spot there is no issue...day end
Day 2: wake up early at 6 am and start travel maximum 7 am very scenic places on the way to hunza like old silk route rakaposhi and dont stay at hunza travel continue to khunjerab stop at attabad lake then passu sust is last area before khunjerab so if you buy any thing then purchase from sust its also very beautiful place then after sust 1.5 to 2hrs drive to khunjerab hope you reached khunjerab till 1 or 2 pm very nice place stay there at half to 1 hrs and 1 think remember after gilgit weather is cold and in sust very cold and in khunjerab tooo much cold khunerab is around 16000 feet high so wear warm cloth when you outside the car and children must wear apter spend time in khunjerab travel back to hunza and stay at hunza stay at karimabad hunza very beautiful place to stay and more scenic i hope you reached hunza aroung 6 or 7 pm...there are reasonable and very hotel there depend on you budget...enjoy night at hunza...
Day 3 : wake up early and visit baltit fort and altit for and eagle nest 3 main places to visit and i hope you visit 3 places in 3 hrs but its depend on wake early after visiting then travel back to naran and maximum start travel at 10am do not more late then travel to chillas then babusar then jhalkhad lulusar and naran with some stop i hope you reached naran at 7 or 8 pm booked hotel and visit naran bazar at night very good and resonable hotel in naran ptdc is also good and reasonable for family....
Day 4: wake up early and then booked a jeep from naran bazar and go to saif ul malook lake its a beautiful and scenic view lake and snow also in june end spend time there and back to naran pack you luggage and start travel back to islamabad on the way back stop at kiwai water fall its a very beautiful place for family...eat trout fish its very tasty...and then travel back to isb hope you reached back at 8 to 9 pm...
its 4 days travel according to your days but remember its very hectic and tiredness travel because you travel 10 to 14 hrs daily....
there is no issue of mobile signal or internet on main area but some area there is no mobile signal like after naran till chillas and the rai kot but mobile service is available main area gilgit hunza naran after hunza there is signal problem....
mostly goods hotels are kids friendly and also good service
so no problem
if you have any question please let me know....