Margaritas (on the rocks)

Tart but sweet, refreshing, and oh yeah, it has tequila. There is a reason that margaritas are up there for all time favorite drinks. Margaritas, when done right, always hit the spot! And I like a quality margarita. I do not enjoy one that is weighed down with a lot of sweet and sour mix. I like lime, agave, orange juice and the flavor of the tequila. And just like my other Cinco de Mayo recipes, this is meant to be a crowd pleaser; both in flavor and in quantity. This will make a large pitcher of margaritas that everyone can enjoy. But since I am kind, I will also break down making a batch that serves 3-4 margaritas for you at the bottom of this post. You know, just in case your not serving or drinking for 10+. :) Um you're welcome.
Ingredients/Instructions (large batch):
4 cups tequila, I prefer silver
3 cups lime juice
1 cup triple sec, Gran Marnier or Cointreau (plus more for floating if you're going with Gran Marnier or Cointreau)
1 cup carbonated water (I know it sounds weird, but like a little bit fo fizz.)
1/2 cup agave nectar
3/4 cup orange juice
1 lime
salt
sugar (colored or plain, optional)
Ingredients/Instructions (small batch):
If you are looking to make a smaller batch, say 3-4 margaritas, use this quanitity of ingredients, and follow the same instructions (below)