Can I do all of this in one day?

The first two would be no problem. I think trying to fit in the last one might be difficult. It really depends if you’re just going to see the waterfalls or doing other things. At Glendalough, just seeing the Monastic city, then walking the trail to the nearby waterfall can take 2-3 hours. It’s an hour or so from Dublin, so between that one place plus driving time it is already about 5 hours.

Separately, on the way to or from Dublin is Avoca. It’s near Powerscourt waterfall. There is a nice woolen mill there and if you watch any British TV shows, Ballykissangel was filmed there.

Is it your intention to spend time at these locations (hiking for example) or simply drive by for photo ops?

I want to explore Glendalough, not too keen on Powerscourt Estate, but I do want to see the waterfalls. My friend wants to visit Glenbarrow, I don’t want to. It’s hard accommodating. We have 12.5 days in Ireland and I want to see all of Ireland. I’m having trouble planning. Thanks.

Suggest getting an early start from Dublin to arrive at Glendalough well before the visitor center opens at 9:30 - that's when the crowds start pouring in as well. Before that you'll have the monastic site and the various walking paths all to yourselves and can wander around at your leisure.
Would recommend skipping Powerscourt if your only intent is to see a waterfall, and proceed to the Glenbarrow area directly. Nice hike there, not sure about anything else.

Skip Powerscourt.....good advice. Glendalough early in the day is a magical dream. It's worth lingering....not racing around.

You can't see Ireland in 12 days.....and if you try you'll only see it on the most superficial of levels. Driving times listed are wildly optimistic. To be safe double them in any instances off the few real highways. Identify want you really want out of a trip.....there is a monstrous gap between literally "seeing" Ireland and "experiencing" Ireland.

If you want to experience it, giving yourself time to linger, reflect and interact with the amazing people..... pick out 2-3 general areas and use those to calmly explore. It is so worth it. Missing another tourist site is nothing compared to discovering a little cafe in the morning, talking with locals and the owners over scones and finding out a local craft group is displaying its wares next to an ancient ringfort....and having an afternoon filled with history, myth, great people and by the end of the day new friends and a deep magical interaction with Ireland old and new. Far better than racing the crowds to get to the Cliffs of Moher, battling the crowds there to quickly "see" it then race on to quickly drive through the Burren on your way to a one night stay near Galway....So you can "see" that.

For what it's worth. We blew it our first trip in a wild attempt to see everything. I barely remember any of it other than being tired and frustrated. Sadly that was the only trip for two family members who never felt they really got to experience much at all. I so wish we hadn't done that with them......the magic only happened when we slowed down on a later trip. That's when things really picked up.

Thanks for the advice; I think I will talk with my friend and slow our trip down and cut out a few places. Good to read about Rock of Cashel and Blarney Castle on other posts- I think I'll cut those out now. I know 12.5 days isn't much time, but I doubt I get to go back to Ireland and want to see northern Ireland as well as Southern/Western. I'll be working on the itinerary most of today. I like nature/wildlife and I'm able to do some hiking; I don't have the stamina I once had due to chemo, so easy-moderate hikes are all I can really handle. Any input/advice would be helpful- and please no snark. Thank you.

You'll LOVE the walks near Glendalough. So beautiful and great for any level of hiking. If you're near Tinahely in Wicklow (reasobably close to Glendalough) there is a beautiful woods with ancient trees - Timnafinogue Woods that is a very leisurely walk and so pretty. The trees will make you believe in Tolkein's Ents !!!!

The southwest is wonderful - hope you get to spend some great time there. The Skellig Ring has some wonderful walking areas from major hills with amazing scenery to leisurely moderate hikes in the Glen that are great. The folks there are so nice. We got invited in for tea so often ! The scenery is stunning.

Hope you have a wonderful trip. It's such a beautiful, magical place.

If you list real specific areas of interest the folks here will gladly give you Great recommendations. Btw - we enjoyed Cashel. It is a ruin.....but fascinating....but it's a couple hour visit not an all day thing. Really depends on your interest in the period. We enjoyed it a lot but the high kings period and medieval history is a real area of interest for us.

Have tons of fun !!!!

We've always had good luck using www.irishtrails.ie to preview our hikes. The walks are broken down by county, and the reviews seem to be pretty accurate regarding level of difficulty, etc.
Suggest picking up a pair of collapsible hiking poles if you anticipate doing much hiking in Ireland - they really make a world of difference ... especially if you have issues with your stamina.
Just down the hill from the Rock of Cashel are the ruins of Hore Abbey, which is worth the walk if you can manage it - no crowds, evocative place, and terrific views of the Rock above. Nice place for a picnic too.