Overnight in Inishmore

No but I wondered if I had spent the night if I would have appreciated it more; if I return I will.

Great idea! We did this 10-15 years ago and loved it. Staying someplace overnight always adds to the experience. Inishmore is magical!

Both times we visited I ishmore, we spent the night. Much better experience, especially if one day has better weather than the other - which happened both times. And flying is the way to go. Both visits, ferries were delayed or canceled due to rough water, but planes still flew.

Yes, we spent two nights in a “glamping” cabin. It was en-suite, had a small kitchen area, a lovely view, and was a short, level walk from the ferry. You won’t regret spending the night. We enjoyed exploring in the mornings before the ferries arrived and things got busy.

https://www.irelandglamping.ie/

We left the rental car in Rossaveal and took the big ferry. Our B&B (which was nearby to Joe Watty's) host refused to accept a reservation for folks coming from Doolin due to the cancellation risk, but she was happy with Rossaveal, which is a larger ferry, crosses a smaller straight, and takes half as long. She may have a different policy for months other than June. We rented bikes and pedaled most of the island. The best part was when the last ferry left Kilronan and the crowd magically disappeared. I think one night is enough to see everything if you don't arrive late and/or leave early.

Good advice from the others. I would only add that since the ferry doesn't sell out you can monitor the weather forecast up to the day of your trip before committing to anything. It does help to visit on a sunny day.
Also good advice from Cyn regarding flying over. Removes any concerns that rough sea states will make for an uncomfortable crossing or an outright cancelation, and adds a scenic flight into the mix.

I would suggest spending at least one night, and definitely flying.

Getting to the island, take the earliest flight you can. This effectively buys you up to half a day (the ferry day-trippers arrive hours later, and the early flight gives you get a great head-start on them). The flights are not expensive, and are absolutely THRILLING (tiny planes, they fly astonishingly low, for the hop that takes no more than 10 minutes…it is a hoot, do not miss it!).

We spent 2 nights on the island, plus most of our arrival day. That was perfect. We rented E-bikes and pedaled all over the island. Most places we went, we saw few, and often no other tourists (because we were able to be there early and late, when the ferry-based day trippers were not present). It’s a magical place.