I'm trying to choose one lens for now, 17-55, 24-105

[Sheiky]

Good to know I must say that weather-sealing for me proved to be more important than I'd ever imagined when I bought the lens. I've been out in a few rainy days, but more important I've had quite the amount of blowing sand and dust to my gear. In those occasions I felt a lot more secure with a weather-sealed lens on my camera. I have used the Sigma 50mm 1.4 in a sandy environment one time and there was sand all over the focus ring and it needed to be cleaned.
In some occasions I didn't even worry about my gear and could pay more attention to taken the photos, which is a great thing. Example of an unsuspected sand-blasting:

Weathersealing ain't that bad by Jan Paalman, on Flickr

[Scott Stephen]

Good to know I must say that weather-sealing for me proved to be more important than I'd ever imagined when I bought the lens. I've been out in a few rainy days, but more important I've had quite the amount of blowing sand and dust to my gear. In those occasions I felt a lot more secure with a weather-sealed lens on my camera. I have used the Sigma 50mm 1.4 in a sandy environment one time and there was sand all over the focus ring and it needed to be cleaned.
In some occasions I didn't even worry about my gear and could pay more attention to taken the photos, which is a great thing. Example of an unsuspected sand-blasting:

Weathersealing ain't that bad by Jan Paalman, on Flickr

Ha! Apparently this kid is a Nikon fan.