As u already mentioned u want to avoid long drives…… so only option left to covers max places in min time is
Bhai take direct flight from Karachi to Skardu
In Skardu either stay or visit Shangrila Lake ( lower kachura)
Also visit upper Kachura lake
Hire any NCP Prado and visit Deosai ( Sheosar Lake) ( it will be a day trip)
Visit Shigar Valley side ( Sarfaranga desert, if u r interested)…. Shigar Fort ( Serena Khaplu)….. Blind Lake….. it will be a day trip
(If u leave early from Skardu u can cover Shigar and also visit Manthokha Waterfall in a day trip
Visit Khaplu and its surroundings ( many attractions)
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Skardu to Gilgit and Hunza ( Stay in Hunza)
Visit Attabad Lake ( also u can stay there)
Visit Khunjerab Top
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On return journey flight from Gilgit to Islamabad and then Islamabad to Karachi
If u want more details, I’m available on 0300-8274291