Morning: Before: diet coke. During: water. After: water; then either coffee (latte w/ skim milk, either hot or iced!) or diet coke.
Afternoon: Similar but usually post-ride is zero calorie zero caffeine fruit-flavored water (key lime flavor is great).

For non-commute rides longer than 1.5 hours or in heat, I'll take something like G2. I like to freeze 1/2 bottle overnight then top it off with cold G2 before leaving the house. It makes kind of a slurpee thing that is really refreshing. I have to drink plain water too; the G2 will cause abdominal cramping / too much fructose if I slam it. I have to plan summer rides where I can buy water/G2 every 15 miles or so, and I still am down about 5# when I finish. Just can't drink fast enough to replace sweating.