The Wicklow way and other hikes in Ireland

I'd suggest you take the St. Kevin's Bus from Dublin to Glendalough and join the walk from there.

Glendalough to where? North or South?

We thought the prettiest hikes in the Wicklow Mtns. were those in the immediate vicinity of Glendalough...either up the valley and back or above the valley along the rim. Can stitch them together for a very pleasant, all-day hike. We explored much of the rest of the NP on day hikes but kept running into clear-cut areas where logging was in progress. Maybe a local guide book could help you plan point-to-point, multi-day hikes.
Our favorite hiking area in Ireland was Connemara, particularly the NP, but we're day hikers only and can't really advise regarding multi-day excursions.
Another suggestion would be the coastline hikes immediately adjacent to the Giant's Causeway near Portrush. The sections of it that we did were quite spectacular, and it was kind of cool to come upon a little bay where they had pulled up the remains of a ship from the 1588 Armada - which you can see in the museum in Derry. You could make a multi-day hike out of that one I suppose...weather permitting. This link: http://www.walkni.com/ has excellent descriptions of the various opportunities in the North, along with some pretty terrific maps. There are a couple of good websites for hiking in the Republic but you'll have to Google them...don't have those links handy at the moment.

We hiked Mount Brandon on the Dingle Peninsula. I can't remember how long it took us but it was several hours. It was totally foggy on the top but it was on the coast and I'm sure the views to the ocean would've been awesome! We saw some of the views through the clouds on the way down. We could see down along the valley though. Great hike.