Cliffs of Moher OR Inis Mor??

I vote for both as well. The Cliffs of Moher just don't take that much time, all told, and they aren't far from the points of departure for the Aran Island ferries. Be advised, though, that weather can change your plans to go to the Arans (you don't say when you plan to travel, but rough water can cancel the ferries, and they don't run as frequently during shoulder and off-season).

Gabrielle, I agree with the others, try to see both if you can. Visiting the Cliffs of Moher will require about half a day, by the time you walk up to the viewing points to actually see the cliffs and get some pictures. Last time I was there, there were signs prohibiting visitors from walking along the cliffs (for obvious reasons). As I recall, there's a Visitor Centre there built into the side of a hill, and you could easily spend an hour or so there. Visiting Inishmore will be an ALL-day trip, including the time for the Ferry rides back and forth. You'll probably want a few hours to visit the shops in Kilronan and perhaps stop for a meal (there's a Hotel / Restaurant close to the Ferry dock). The sweater shop there is reportedly the largest one in Europe! There are several options for touring. You can choose a "conventional" tour in a Van (the drivers are very entertaining), a tour in a pony wagon or rent bicycles. Which tour to choose will likely depend on the weather. The Van tours usually provide some time to hike up the hill to Dun Aengus (BE CAREFUL at the edge, as it's a LONG way down!). There are a few souvenir shops and a small restaurant at the base of the hill (the soup is excellent!). Whichever option you choose, you might pack along a small bottle of Bailey's for a treat during the day. Happy travels!

The Cliffs are a "site." You can walk along the top and/or take a short cruise out of Doolin. It's hard to imagine spending more than an hour at the top and the cruise is about an hour. Inis Mor is a longer term time committment but it puts you into an area of Irish culture with some things to see there, of course. See both if you can but none of us can see everything.

My vote is for both. We saw both on our first trip to Ireland and didn't feel like we had a "been there, done that" experience when visiting either.

I agree with all above- if you can do both I would. My advice for choosing between the 2 is definitely Inis mor- the island is amazingly beautiful and it is truly more of an experience vs. a sightseeing stop.

If you can only do one and the weather is good, go to Inis Mor. It's like visiting another world, and I wouldn't miss it. I thought it was spectacular. The Cliffs would be easier to fit into another trip.