Like the vast majority of you, I believe I use the right tool for the job at hand. And I do have fly rods from 6' to 10', and use them all.

I guess since I really enjoy fishing the smaller headwater trout rivers so much, I seem to keep having 7'9" - 8' 4wt rods showing up at my house. Kind of an OCD thing, I suppose.

Thanks for all the great replies!