Thanks everybody for all your replies...very useful indeed. It seems crazy that I wasn't able to find anything at all on the web about this before posting on boards.ie!
I would love to get a lift with my girlfriend in the mornings, cut out parking costs, fuel, traffic etc. but unfortunately she works 8.30 to 4.30 and I work 9 to anywhere between 5.30 and 7.30. So that is out of the question.
As long as there are spaces available at Stillorgan that seems fine to me. The €4 charge is crazy, but at least if I'm not able to find any free parking around I have that option as a back up plan.
Great news about the ten minutes from the M50 too, that is a relief. I am hoping that the commute from Kilcoole/Newtownmountkennedy should be only about 30 mins (if that?!), but I could be dreaming...I will just have to check it out. Anybody have a view on this?! Planning to leave house at approx 7.45am to be in work on Clarendon Street for 9am.
Thanks again everybody, and if anyone had any other comments I'd love to hear them.