My partner and I are using a work trip to Belfast as a launching point for an Ireland vacation. For scheduling reasons, we have to begin (rather than end) in Belfast (4 days), but are then thinking of traveling south/southwest Ireland for about a week before finishing in Dublin. I'm trying to figure out the best options for flights (I fly from MSP), car rentals, and possible trains, keeping time and money in mind. We don't necessarily need a car while in Belfast, however we would like to drive the Antrim Coast and possibly inland Northern Ireland, so would need a car for that (the train/bus option seems less than ideal).
The simplest option for a car rental would be to fly into Dublin, rent a car, drive straight to Belfast, and keep the car until returning to Dublin (I know there may be a fee for driving into NI, but I have read it's often minimal). However, I know people warn against driving after a transatlantic flight, especially when it's unfamiliar driving on the other side of the road. This option also involves the most driving - my partner will be doing the driving, but still, I'd prefer him to be able to enjoy Ireland!
Another option is to fly into Belfast and out of Dublin. Begin the car rental in Belfast, then return it someplace in Ireland (possibly Cork, then train back to Dublin). As noted above, I'm assuming this option might be the priciest with one-way fees from NI to Ireland. Does anyone have experience renting a car in Northern Ireland and returning it in Ireland? I've been trying to find out information about added fees for doing this, but am finding different information depending on the rental site. I'd prefer not to be surprised at the car rental counter.
A third, more complicated option could be to fly into Belfast and out of Dublin. Rent a car just for a day in Belfast to do area sightseeing. Then, when done in Belfast, take the train to Dublin and begin a car rental there (or possibly even take another train from Dublin to Cork, and renting from there to lessen the driving).
All thoughts and advice welcome! More than any other trip I've ever taken, planning this one feels like quite a puzzle.