In a small saucepan, combine sugar and 1 cup of the water over medium-high heat. Bring to boil and stir to dissolve sugar completely, then remove from heat. Allow the simple syrup to cool to room temperature, then cover and refrigerate until completely chilled.
Meanwhile, juice enough lemons to get 1 ¾ cups of lemon juice. The number of lemons needed will depend on the size of the lemons you have but generally speaking, 10 lemons will do the trick. Remove any seeds from the lemon juice, but leave the pulp. In a pitcher, stir together chilled syrup, the freshly squeezed lemon juice and the remaining 7 cups water.
Add sliced lemons and ice to the pitcher for presentation.
Notes
You can adjust the amount of water until you get the level of sweetness or tartness you desire. I like to add a lot of ice and hold back on some of the water at first so that the lemonade doesn't get really watered down.