Alternative to Cliffs of Moher

There are a number of other options, but one way to beat the crowds up at Moher is to book an evening boat trip along the Cliffs from Doolin - several people here have raved about it and it does sound like a great alternative.
Sieve League up in Donegal is stunning, and relatively uncrowded, if you plan to be up there anyway.
There's a pretty cliff walk in Kilkee just to the south of Moher, and the coastal drive to get there is quite pretty on a sunny day.
The Kerry Cliffs along the Skellig Ring Road is worth a stop if you plan to drive the ROK.
The cliff at Dun Aengus (Inishmore) is pretty dramatic too ... especially if you stand anywhere near the edge.

Thanks you. It looks like several good options. Is the Dun Aengus (Inishmore) on the Arran Islands?

What Robert said. We enjoyed the sunset cruise out to the Cliffs/Moher (bought tix in the morning, but that may have been unnecessary), followed by dinner and music in Doolin. Also can second the tip on the Cliffs of Kerry near Portmagee on the ROK; beautiful, impressive surf, and relatively few other tourists (May 2018).

Yes, Inishmore is one of the Aran Islands, most easily accessed via ferry from Rossaveal - west of Galway.
The Aran Ferry company runs a shuttle from Galway out to the ferry landing for a small fee. Very convenient if you don't have car, or just prefer the door to door service.

Echoing some of the other comments on this thread—we found Slieve League Cliffs in Donegal and Kerry Cliffs near Portmagee more impressive than Cliffs of Moher.
Our cruise experience to see the Cliffs of Moher was underwhelming even though it was a beautiful sunny day. Crowded boat with too many people jostling for position to take selfies.
We opted for Inishbofin instead of Inishmore and had a wonderful day of hiking on the island.

I haven't been to the Cliffs of Moher. I'm turned off by the tourist trap buzz I hear.

I enjoyed the Cliffs of Kerry on my trip in May. I was a little disappointed that it cost 3 euro and their open hours didn't include sunrise or sunset. The cliffs and displays are nice and I was either alone or with a couple other people the entire time there.

I also enjoyed the cliff views near Kinbane castle near Ballycastle in the north. There are few people there, it's free and always open. The cliff views at sunset were very nice. The next morning we had nice views (not quite as spectacular) at Carrick-a-Rede. We were there 1/2 hour before the ticket booth opened so just walked to a view of the bridge and back. For an extra 12 euros (and a half hour wait) we could have crossed the bridge and walked another 100 feet - probably not worth the extra time or money.

The cliffs at Dun Aengus on Inismor are neat. There is no guardrail so I preferred looking up or down the coast, from ten feet away, to looking over the edge. If I had more time, I might have preferred the other ring fort. Dun Aengus also has an admission charge and limited open hours.