The 70-200mm lenses are probably the most versatile. They are a great travel lens… able to do portraits, compress landscapes and capture images you can’t get closed to. The 2.8’s are a bit of monsters… over 3 lbs. But if you can carry it, it is certainly worth it… as is the IS if you can afford it.
I have a love-hate relationship with this lens. I love the images it produces but hate how damn heavy it is. I also hate that it is white. I wish there was a black option like Nikon. It is purely cosmetic but I feel it is so conspicous when you whip out this enormous white lens. I know the 1D is already inconspicous itself… but the bazoka being white does not help. The lens is super solid, weather-sealed and did I say it produced amazing images!