There's a few islands off Sligo around Inishowen that I'd love to get to with early Christian settlements on and beautiful cross-slabs.

The rock-cut passage tomb at the top of Croaghan (I think) in Sligo is a bit of a bitch to get up to.

Like Ken, I'd love to get to that four-poster.

I've done quite a few that involve a 3 mile hike up a hill to get to, and like bawn79 I too usually go via the worst route possible!