Portmagee or Dingle for two nights

I would for sure head to Dingle. There really isn't much in Portmagee beyond the Skellig Michael cruises and experience centre. I think it took us 1.5 hours to drive from Portage to Dingle so quite quick ( by North American standard anyways)

Greetings from Dingle
I'll be brief. You desperately need to spend that second night in Dingle. To avoid Dingle in favour of an extra night in Portmagee would be akin to tragic.
Im speaking as Irelands most experienced tour-guide, and not as a Dingle resident.
Le meas/with respect
Stephen McPhilemy
Rick Steve Ireland tour-guide
Dingle and Derry

I agree that given your limited time spending the extra night in Dingle would be your better choice.
That said, there are a couple of short side trips that you might consider after your boat trip out to the island: We considered the Skellig Ring road to be a truly unappreciated little gem of a scenic drive. It's a short spur leaving Portmagee that will eventually take you to the village of Ballinskelligs, where there are the ruins of a castle and an old abbey - it's where the monks from Skellig Michael relocated to after they finally departed their island centuries ago. And no crowds - the tour buses don't go there - so if you're looking for a slightly off-the-beaten track excursion you might consider it. Some terrific, picture postcard views of the Skelligs from the headlands along the way too.
The other possible enroute stop is the Gap of Dunloe - for our money one of the prettiest little glens in all of Ireland, and one of the most pleasant and scenic walks you'll ever take. Need to time it to arrive early (before 9:30 AM) or late (after 4 PM) in order to miss the crush of tour buses and day trippers that tend to clobber it (and take up all of the available parking) around midday.

Many thanks for the quick replies, based on your information, I'm going to make the change.