Westport and Connemara

Ashford castle and the Hawk Walk was the highlight of our trip for my sister. I would put this on your list.
Westport was the biggest disappointment for both of us. Very tourist oriented with a complete range of souvenir shops throughout. I would take it off your list.
The Aran Islands were a wonderful experience and absolutely beautiful. We went there instead of Doolin and were quite satisfied. Is it “better?” I can’t tell you.

Consider the pretty little market town of Clifden as a base. It's located about an hour by car NW of Galway, and is central for the Sky Road scenic drive just west of town - one of Ireland's best. From there it's also easy to do the Connemara Loop drive, which will take you clockwise up to the National Park - which has pretty hikes up to a feature called Diamond hill with spectacular views of the countryside all the way to the sea. Continuing around you'll drive thru some of the prettiest countryside in Ireland to Kylemore Abbey and then finally arriving in the village of Cong which is where Asheford Castle is located. Aside from the Hawk Walk you can stroll the grounds of the castle and maybe have lunch or tea while you're there. There are the ruins of an old abbey in the town itself which is quite picturesque - still looking like the movie set it was back in the early 50's for the old John Wayne/Maureen O'Hara film "The Quiet Man" which was filmed there. It can be fun just walking around the village trying to identify locations from the movie.
Clifden is handy for the ferry from Rossaveal out to the Aran Islands as you mention. Others here have recommended flying which removes the odd chance of ferry cancellation due to high sea states, plus it adds a scenic flight into the mix. Haven't done it ourselves but we have it bookmarked for a future trip. Another excursion from Clifden is the ferry out to the island of Inishbofin ... one of Ireland's better kept secrets. The ferry departs from the village of Cleggan - only about 15 minutes by car from Clifden.
For a little longer excursion you could head north to Killary - the inlet there is Ireland's only fjord - and a little north of that is the Doolough Valley and memorial which we thought was one of the most evocative places in Ireland because of the history of what happened there. Can google it to see if it might be of interest.

Aran Island Ferries offers service from Galway town and Rossaveel to the Aran Islands. Its ferries are much larger than those departing from Doolin and have spacious indoor seating.

https://www.aranislandferries.com/

For a more adventurous trip to the islands across choppy Galway Bay from Doolin, you have two options. The first service below has a ferry with the intriguing name of "Happy Hooker."

https://www.doolinferries.com/

https://www.doolin2aranferries.com/

I recommend a trip to the village of Leenane, nestled between three mountain ranges in one of the prettiest spots in Ireland. It's at the end of Killary Harbor, which has the country's only fjord. While there, have dinner at the Blackberry Restaurant, which serves the freshest and most delicious dinners we've had in many trips all over Ireland.

I concur with Robert's suggestion to visit the Doolough Famine Memorial. It's a few miles away across the harbor in an absolutely desolate and peaceful setting in County Mayo. A bit further on and just outside Murrisk is the even more moving National Famine Memorial with a replica sculpture of a famine ship. It's also across the street from Croagh Patrick, which you can walk up in about two hours.

https://www.leenanevillage.com/index.html

https://www.blackberryrestaurant.ie/

Thank you for all of the wonderful advice and suggestions.

If you decide to see Killary fjord, Killary Sheep Farm is at the opposite end from Leenane and I highly recommend it. They have sheep dog herding demonstrations, sheep shearing and lamb feeding—fun for kids of all ages. Check their website for opening days/hours and book ahead. https://killarysheepfarm.com/
We also really enjoyed our day on Inishbofin which Robert mentions above.