Feasible Itinerary?
 

Curious if my itinerary would be feasible for my trip from Dublin-Galway-Dublin

Day 1:
arrive in Dublin
rent car
drive to Rock of Cashel
drive to The Burren
drive to Galway

Day2:
Drive north to Ross Errilly Friaray
-Cong Village/Ashford Castlle
-Kylemore Abbey
-Connemara natl forest
back to Galway

Day 3:
Aran Islands/Cliffs of Moher
Dinner at Dunguaire Castle Show (8:45pm)
back to Galway

Day 4:
Drive from Galway to Dublin stopping at Seans Bar along the way and possibly the Hill of Tara before checking into Dublin hotel and returning Rental car around 4:30pm

Are you flying in to DUB long haul?

If so, getting off a plane and driving 5.5+ hours (plus your stops - so a 9 or even 10 hour day) is beyond crazy.

You only have 3.5 days really so I'd drop the southern loop

Does this sound better?
Day 1:
Dublin Airport arrive
rent car
drive to Galway stopping at Sean's Bar for lunch
relax/enjoy Galway
Drive to Dunguaire Castle for dinner

Day 2:
Ross Eirrily Friary
Cong Villiage/Ashford Castle
Kylemore Abbey
Connemara Natl forest
back to Galway

Day 3:
Inis Mor/Cliffs ferry
*if wx causes no ferries explore Cliffs from top/Doolin

Day 4
Drive to Dublin/explore possibly go to Hill of Tara?

Day 5
Explore Dublin

Day 6 fly to London

We plan on doing something similar to what dtatum suggests next June at the end of a British Isles cruise, we'll have two full days and 2 half days based in Galway. We rent a car at Shannon and drive to Galway for three nights via the Burren. The Cliffs and Inis Mor on Day 2 and Connemara on Day 3, or vice vera, depending on the weather. Morning of Day 4 in Galway before driving up to Dublin for another three nights.

dtatum: Still asking - are you flying in long haul?

If so I do not see how you could manage 4+ hours of driving plus two heavy meals including a medieval banquet on your arrival day.

The ferry to the Arans from Doolin is VERY weather dependent. I suspect the Cliffs cruise is, also. Agree with janisj about the first day if coming off a long-haul flight.
It IS better than the original plan though. The Day 1 on it would likely have left someone dead.
You could do the Medieval banquet at Bunratty after the Cliffs -- but spend that night in either Ennis or Bunratty.

Thanks guys I am flying in from US to Dublin with a layover in Toronto. I think day 1 we will just drive to Galway and then stay there for the day...plenty to see there and also ability to just relax. we have decided to nix the castle banquet since it requires us driving back to Glaway super late so just gonna nix that alltoghether. The main reason to do the Aran ferry from Doolin is to also see the cliffs the ferry from Galway doesn't do a Cliffs tour and then you are back in Galway...I realzie the ferry is wx dependant so if it doesn't run that day we will just do the land walk of the cliffs and explore Doolin instead...and we are also just going to drive straight to Dublin on the last day and go to the Guiness Storehouse (we have a hotel in Dublin that night). Also does Sean's Bar serve food? or is it just drinks?

I believe it's mostly drinks, music and museum, rather than an eatery.
There are a number of restaurants nearby, or just across the river -- and a nice little café, practically next door.
Know though that it's a morass of one-way streets.