I really wanted to buy all the seasons on dvd, but since 3-4 episodes are on per day on Spike TV, I figured that I wouldn't watch the dvds as much as I would the regular tv show on Spike, so it really wasn't worth it to me.
Anyway, on Amazon it shows that Miami and NY are both widescreen for the first season, but as for the original CSI I think you're out of luck.