The Round Tower at Glendalough
It's hard to get this right without resorting to multi-shot HDR, and I look at my tripod and end up leaving it in the car, because it's awkward to carry and there are hills. So ultimately I end up taking a single shot, and biasing the exposure down to minimise the risk of a plain white sky.
And then in a situation like this, where the sun is behind those clouds on the other side of the tower you almost get a silhouette and have to bring all the shadows back up.
For the last few years I've used Rawstudio for processing my files, but recently I've started to get the hang of +darktable and I'm definitely finding there are things there that I couldn't easily do before. I used to have a problem with how it handled 10's of thousands of raw files across a few hundred directories, but I guess one or both of us have changed from those times and now it seems to be fairly manageable from that point of view as well, although I'm still using other tools for most of the actual file management and just using darktable for the raw -> jpg processing, but maybe one day I'll learn all the shortcut keys.
So anyway, this is the kind of thing that makes it worthwhile. Not that it's all that wonderful a photo, but I'm pretty happy with it like this and I know I would've given up in frustration previously.