We will be in Dublin for a day on a Sunday. Is there enough to do between 9:30 and 12:00? Or should we plan to leave for the countryside in the morning?
The Trinity College website did list a summer tour schedule (through September 22nd): http://www.tcd.ie/Library/bookofkells/trinity-tours/
There is more than enough to do in Dublin in that amount of time! You could take a 90 min. hop on/hop off bus for a narrated overview of the city, walk through Trinity College and down Grafton St., or down to Merrion Square to see the Georgian houses. I am not sure of Sunday museum schedules, but they may be open, too.
I have not been to Dublin yet, but have been looking for similar information as I will have a full day in Dublin on a Sunday as well. The hop on hop off buses start at 9 am. The Guiness Storehouse opens at 9:30 and Trinity College Tours start at 10:15.
Unless things have changed, Trinity College tours are only available during the school year. And since you only have a morning, I wouldn't suggest the Guinness Storehouse (actually, I wouldn't recommend it no matter how much time you had).
It really depends what your interest are? I did enjoy the Guiness storehouse tour and this prison's tour:
http://www.heritageireland.ie/en/dublin/kilmainhamgaol/ for about 6 euros...a small group tour...good deal!
Kilmainham Gaol is well worth the time. The Guinness Storehouse not so much, particularly if you only have the one day.
Was just in Dublin 2 weeks ago. Even though it was HIGHLY recommended, I would pass on the Book of Kells. I was disappointed and thought the admission price rather high. Would be better to use your time on a Hop on Off bus tour, for a good over all look of the city.