I aim for between 85-100 oz a day for water...really. They say 1/2 our bodies are water as we get over 30 so aiming for 1/2 your body weight is good (there are other things that factor in too but it gives you a good idea). If you do some decent cardio it helps you drink more too.
As for Crystal Light...be careful...that stuff is laced with aspartame (same stuff in diet coke). That stuff's dangerous! Don't take my word for it though, check out
Aspartame Dangers Revealed!. I mention this not as spam ok--I've suffered from aspartame poisoning for years and you cannot imagine how great you feel once you get that crap out of your system. Dr. Janet Hull operates that website. Trust me it's a must-read.