6 nights in Ireland - from Dublin

Depending on where you are flying from, you will likely arrive in Dublin in the morning and quite jetlagged. That means you will need to nap until later in the day and perhaps have some time to walk about and have dinner before the day is over. That leaves you 5 full days with Mar. 31 back in or near Dublin so you will be close to the airport for your flight home.

If you haven't bought your air ticket yet, consider flying out of the west so you don't have to backtrack just for the flight.

If you spend 2 days sightseeing in Dublin, that will give you 2-3 days for the rest of the trip. Not enough time to cover all of your wish list . Choose the one or two places most important to you and just go there. If you fly home from the west, you might be able to add one other item from your wish list.

If you spend 3 days in Dublin, you can make one a day trip to Glendalough/Wicklow Mts. quite easily.

Enjoy!

With a 5 yr old, and as a mom myself, I would choose the option of day trips from Dublin. You can head north to Newgrange and Belfast and then head south for Wicklow, Powerscourt etc.

With such a short time I'd choose either Dingle Peninsula or Ring of Kerry, not both. People on these forums generally praise Dingle.

Thanks all! Unfortunately we already booked our flight so don't have the option of flying out from the west. We are definitely leaning more toward the Dingle Peninsula versus Ring of Kerry.
Day trip tours from Dublin seem like a good option. Does anyone have any tour companies they'd recommend?

Dublin to Dingle by car or bus takes almost 5 hours one way - not really a candidate for a day trip from Dublin.
Given your very limited time and the prospect of traveling with a sleep deprived and cranky 5 year old your better bet is to do as diveloonie suggests - stay in Dublin and rely on day trips from the city to Glendalough, the Wicklow mtns., and maybe the Boyne Valley, Tara and Newgrange just north of the city. There's also the option of the 2 hour train ride up to Belfast. Would be easier on all of you I think. Besides, there are more and better distractions for your son in Dublin than out in the countryside. Am thinking in particular about Dublinia and the museum featuring the "bog man" which would fascinate a 5 year old.
As others have opined, I really don't think you have the discretionary time to waste just getting to Dingle and back this trip. Suggest keeping it simple for a first visit and leaving the charms of the west of Ireland for another trip.

As others have mentioned you have very limited time, and trying to get all the way down to Dingle and back is not the best use of your time. Stay in Dublin and do day trips to Newgrange, Glendalough, maybe take the train t Kilkenny or Belfast. You will get a good taste of Ireland this way without the stress of driving and being in a rush to return to Dublin.

Thanks all - really appreciate all the advice!