Glendalough is not well served by transport,, there is a local company who run a limited service but I would say that leg definitely needs a car  http://www.glendaloughbus.com/timetable.aspx

I'm with Bob on this one. If you are going to spend more than one night in the Glendalough area a car will let you explore so much more. Pinewood is up a hill off a small seldom used road. No sidewalks. It would be very dark at night. Riversdale is walkable either by the stepping stone bridge across the river or main road.

Right in the village is Lynham's of Laragh and next door to the Wicklow Heather Restaurant is Wicklow Heather House, which looked nice when I inspected it. If you have no car I think I would go with one of those two. Although there is free transport from Pinewood and Riversdale back and forth to the Wicklow Heather Restaurant.

Without a car I think I would do Glendalough for 2 nights. Not a weekend! They tend to be crazy full of tourists. Do mid-week. There is plenty of hiking around the area. With no car I think I would opt to stay at Heather House. As you know, Laragh is a very small village and you can walk everywhere from Heather House.

Maybe check out Fat Steve's Blogs http://fatstevewalks.wordpress.com/walks-by-busrail/  Bray Head walk is a good way to spend a day.