4d3n is too short for these places.. Is quite a distance to travel to these few places... I would suggest malacca n kl.. Penang is very far from kl..have you booked air ticket?
KL同馬六甲約一小時車程,你可以join local tour,會方便啲,或者你都可以from KL搭coach,都ok架。 建議你最好weekend去比較熱鬧,有個著名既jonker street(雞場街)。。如果去埋penang,五日四夜都ok既,但只限於走馬看花囉!Distance from KL to Penang is approximately 4 hours... 希望幫到你。