Well, I recently returned from Dublin and here's my report as promised!...
Upon arrival, I staved off my impending jet lag by walking a few holes at the Portmarnock Links (the Langer hotel course). In my opinion, this course is under rated and overlooked because of its neighbor, the "real" Portmarnock. There are plenty of interesting ripples in the fairways (perhaps manufactured by Langer et al) and some decent dunes in a rather compact routing. A nice variety of holes though and a strong finishing trio of #16-18.
Next morning, bright and early at Royal Dublin. Despite the nice pictures earlier in this thread from Aidan Bradley, I still found the course rather flat altho the holes got better as you worked your way out beyond #4(maybe?). A true out and back links, the front nine was almost entirely downwind and then you make the turn... wow. The wind in your face all the way home makes the back nine a lengthy challenge. If the Portmarnock Hotel Links is considered under rated then I would have to say Royal Dublin is a bit over rated.
The last day was spent at The Island GC. You're thrown into the impressive dunes right away on the first tee, a great view over the estuary on the next tee, and plenty of quirk (how about eight consecutive par 4s to begin the round?!) and then on to the back nine... even better with a great variety of holes. Highlights were the par three 13th out to the tip of the island (a brief timeout for a history lesson on your way to the next tee where the boat used to ferry early members across the estuary), then the much written about 14th with its impossibly narrow fairway which is followed by the really good par 5 15th with a green nestled at the base of an amphitheater of dunes (reminded me alot of Doonbeg's opening hole). Overall, a great golf surprise!
My biggest concern going into this was the weather. Not a problem-- a bit of "all four seasons in one day" but very pleasant conditions for walking and carrying your own bag.
Based on the tremendous deals for airfares/hotels/green fees, the proximity of everything to Dublin and the airport (i.e. easy 20 minute cab rides) and the high quality of golf, I'd highly recommend it as a "quick" getaway. (Plus I didn't even include Portmarnock Golf Club-- but found out as I was leaving that they had just reopened the front nine and gotten rid of the artificial squares of turf to hit off of.) Add in Portmarnock and it's a "can't miss" holiday!