This is kind of obvious, but I have found that the best way to study the textures in various texture sets is by opening the folder in question in Windows Explorer and setting the view mode to tumbnails. This is the easiest way to get a good general idea of the different textures in different sets, and a lot easier and faster than in Radiant, for sure.
Of course this assumes that all the textures are unpacked from the asset file, but I guess most mappers have done that anyway.
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Frozen by ICARUS
Frozen in the past by ICARUS