A couple of pointers
1: Decide if it's a 1 or 2 day event. (With an eye to available accomodation and entertainment (Pub

)
2: Plan a route which includes a number of scenic or drivable features ( quiet road with hairpin or such, downhills etc)
3: Pick a date and STICK TO IT!, post it to the calendar making sure it doesn't impinge on any other event if possible.
4:Announce the run on the forum and Hassle....sorry, REMIND the members at every opportunity.
5:Don't forget to include somewhere to meet up with a restaurant or coffee shop...driving a 5 has an effect on the appetite (this hasn't been scientifically proven, but it is a good excuse for a gathering)
6: End the run as near as possible to major road which will make the trtip home easier for those who cant read maps on the back of napkins,
7: during the run itself have plenty of stops for chat, tyre kicks etc.
8:Dont worry if only a small number turn up, though a Kerry run is not likely to have that concern. A run 0f 3 or 4 cars can often be more manageable/enjoyable than a convoy of 15, Any number is acceptable
9:Before heading off, check with everyone that fuel levels are sufficient for the route, you'd be surprised
10:Enjoy it!
Come on lads, add a few more to the list
John