It just occurred to me that because of the pick-up and drop-off times I had originally scheduled, I could actually pick up my rental car the night before we leave Dublin in the city, rather than have to take an early morning taxi out to the airport, and incur no extra charge.
I guess I'm getting tedious with this issue but:
If I already had a car (picked up the night before) and parked it nearby (JurysInn Christ Church) and departed around 7:30 or 8 for Glendalough, how hard is it really to drive out of town and get on the road? Is the difficulty because of rush hour (Wednesday morning) or confusing streets and road signs, or both? Would I still do better going out to the airport and taking the loop road to avoid the city traffic?
The problem was I didn't want to wait till 10 AM for the city rental location to open up. Now that I have realized it wouldn't cost me more, I'm thinking, Why not get the car the night before? What do you think?
If you get the car the night before leaving Dublin you should park in a parking garage. Parking in Dublin (depending on which garage) is expensive.
You will encounter rush hour. The signs in Dublin (if they exist at all) are high up on the sides of buildings. There is also a lot of construction which means that roads and one-way systems change frequently. The best advice I can give on doing that is to start as early as you can and get exact directions written out from your hotel so that you can get on the right roads without fumbling around.