Re: Visiting Karachi
Arena (A must see, I always enjoyed bowling there)
Sea-view (you should visit but you wont find it clean anymore..)
PAF Museum (not in my top of list but again if u’v never been here, u can enjoy)
Al-Habib Restaurant or Al-Sajjad Restaurant (at super highway but you will enjoy a night out there with family, certainly)
Quaid-e-Azam ke mazaar p ab sirf dates hoti hain to unless you dont have a bf in karachi..i wont recommend you 
BurnsRoad if you want to eat some chatpati Chaat or dahi-bhallay 
French beach is what I have heard now closed.. 
dont know the reason verna French Beach and Neelum Point are gorgeous!!
Hocksbay/ Paradise Point/ Sandspit (not sure about sandspit) are good places too!!
Dreamworld Resort
Javed Nihari ki Nihari bekaar hogayee hay STA 
its no more same!!
and Gelato Affair, so far best italian ice-cream parlor.. (I have been to Karsaz branch, dont know if other branches exist 
)
Shopping purpose:
Tariq Road
Zamzama
Park Towers
Forum
I have never been to Hyderi Market, but heard its a good place for shopping too 
Aur kuch yaad aya to batadungi