2.5 Day driving tour Dublin to Northern Ireland and back to Dublin

You won't see much of Derry with this agenda. I highly recommend the Museum of Free Derry and the Bogside Murals (with or without a guide). I found it to be much more engaging and informative about The Troubles than the black cab tour. I wouldn't want to have a car in a big city like Belfast (traffic and parking). Depending on the time of your return flight, I would consider shifting Newgrange to the last day and stay nearby (Trim, Malahide, Drogheda). It's recommended to be at the Dublin airport 3 hours ahead of your flight because you will go through pre-clearance for US customs and immigration.

It feels a little pinched to start. I feel like using this plan you’re not actually doing much in Derry. I think I’d make a choice between Newgrange et al, and Derry. You could make a case for sleeping in Bushmills or something if you’re spending so little time in Derry.

Your Belfast time is solid. Highly recommend the Harrison Chambers of Distinction, great hotel with free parking in back. Orto Pizza around the corner from there was so good we went twice.

I am sure you are going to love beautiful Northern Ireland.

This is a place I visit regularly, and to me, this itinerary is not reasonable. The drive from Bru Na Boinne to Derry appears to be 2.5 hours (and could easily be longer)- you will barely have any time in Derry at all, and then have to do another 2.5 hour drive the next day. I would either just concentrate on Derry and the area around it, or just Belfast/Causeway Coast. I understand you have personal reasons for wanting to visit Derry but if it were me that's the part I would cut. Or, keep Derry and combine it with a visit to Enniskillen and the Lough Erne area which is also in the western end of NI and very beautiful.

Assuming you are just wanting to visit just Newgrange and the Visitor centre, then this is going to need a couple of hours. Don'tforget you will need to factor in time for lunch somewhere. Newgrange to Derry is going to be a good three hours drive without any stops. As already pointed out, this isn’t going to give you long in Derry.

You don't say when in September this is - sunset in Derry is about 8.15pm at the start of the month but by the middle of the month is going to be about 7.45pm. By the end of the month it is 7-7.15 ish.

Another (huge) vote for the Harrison Chambers of Distinction in Belfast…literally one of our all time favorite sweet little hotels. We weren’t driving at that point of our trip, but it’s out of the busy downtown a bit, just down from Queen’s University and as mentioned, has handy parking in the back. And in Derry, McCrossan’s walking tours of the walls are wonderful.