With some film lenses I'm more likely to use a filter, partially because there's quite a bit of blue in the light here and using fuji film can make it even more apparent, so I sometimes stick an 81a on to knock that back a bit.
With Digital no, I used to religiously use them, until after taking pictures from a live music event I got reflections of the lights from the filter, since then never.
I use lens hoods most of the time though, so that addresses most of my flare and minor protection concerns.