jtstar everyone has a different sweetness preference. The best thing to do is get a container about the size of a qt jar and keep adding sugar till you get to the level of sweetness you're looking for. Keep track of the amount of sugar you are adding so you can maintain that ratio in your carboy. When you are happy with the amount of sugar take a sg reading with your hydrometer. Now you have a sugar to volume of wine ratio and a sg reading to work with. If someone else is going to be sharing this wine with you involve them in the testing.
what I have is one gallon of Cranberry and White grape mix and one gallon of Cranberry and I am thinking that at this time all I want is one bottle of each to be semi-sweet and sweet then leaving the remaining one half gallon dry of both gallons