We just had this same discussion over on Karen Russell's "The Photographer's Workshop" forum . . . and Karen recommends using a lens hood ALL THE TIME. AND for EVERY lens. Regardless of the shooting circumstance (EVEN when trying to create lens flare). Mainly for PROTECTION but also to reduce stray light from entering the lens from the side.
As for the UV filters . . . those are typically used for protection as well (at least the clear ones are). And you need the high quality lens filters in order to minimize reduced image quality. I have a high quality UV lens filter on my Nikkor 18-200mm 1:3.5-5.6 AF-S and will probably use it in conjunction with my lens hood or take it off altogether. I've not decided yet. Thinking I'll take some test shots and see if there is a reduction in image quality when using it and if there is well . . . off it comes. Otherwise I'll leave it on. Figure I can't get enough protection when it comes to my lens. If you know what I mean.
