I like all the Ideas about Tanks and Crusies and everything, and agree that putting children in would just be sick but it would be verry cool if:
you could choose a job
Select what type of face you have and what you wear (Like sa), your skin colour and things like that
There should be more Planes and Boats and Trains
You can customize any car (even trucks but only the Interior)
a place where you can buy cars like Sunshine Autos and a place near the Sea where you can buy Boats
you can buy an airfeild Assest like SA but one of the Main ones like a Private airfeild
you can see like a short Cut-scene when you die where you get pulled out of the ambulance and taking into the hospital and you see yourself going into surgery and then it ends or something like that and the Same when you get arrested.
Thats all i can think of for now.