We will be in Ireland in September biking through the Connemara region. We will start in Dublin for 2 days before heading to the 9 day bike ride which is beginning and ending in Galway. We have 4 days before heading back to Dublin to go back to US. Where should we go? Dingle Peninsula area or Belfast? Don't think we have time to do both, we are not renting a car.
I think it depends on what you want to do. More biking or hiking? Dingle. History, city/urban experience? Belfast. Unless “Belfast” is shorthand for Northern Ireland. In which case there’s plenty of outdoor activities to do in NI.
If you are not hiring a car, you need somewhere that has good transport links or else plenty of day trips to occupy you... Belfast would work. I assume you realise this is Northern Ireland and uses Pound sterling rather than euros?
Dingle - I have found this one day archaeological tour
Alternatively Begleys off a series of one day tours picking up from your accommodation . They don't quote prices on their website, I assume they are based on number of people booking the tour and could work out expensive...
There is also Killarney . Have a look at ideas on this website for day tours from Killarney.