We are heading back from Doolin on day 6 and looking for a place to stay b/t Doolin and Dublin (I think it will be too long a trip to make it all the way to Dublin that night after spending the entire day exploring Inishmore. Can anywone recommend a good stop over point? Kinnitty castle is an option that is about halfway. What do you think of this place? Other recommendations?

It takes less than five hours to travel from Doolin to Dublin. Are you considering setting off in the evening after a visit to Inishmore?

I'd go via Galway, which would mean than Kinnitty would be off your route. You might consider a stop near (rather than in) Athlone and a visit to Clonmacnoise in the morning before continuing the journey. One possibility, especially if you like good food, is http://www.wineport.ie/ (I haven't stayed there, but will go out of my way to eat there).

Kinnitty Castle is in receivership or foreclosure, I believe, and not open as a hotel at present.

When are you going? We are staying at St. Ruth's Farmhouse on June 22. It's just outside Athlone towards Brideswell. If you're going after we are, I will get back with a review, if not, here's the website and you can decide for yourself.
http://struths.com .

I would seacond Athlone as a good half way point. Plenty of hotel and B/B options in the area. Would recommed booking in advance though.