Would like to stay one night in a castle. Any ideas?
Dromoland Castle
The Irish Landmark Trust https://www.irishlandmark.com/ has some unique properties that might be of interest - including a few castles.
They're self-catering places however, and may require a minimum 2 night stay ... but would probably still cost less than a night at Dromoland, Ashford, or any of the other true castle-hotels in Ireland.
Clontarf Castle in Dublin (more like the outskirts of Dublin, 15 min cab ride into the main touristy areas) was lovely and felt like an affordable luxurious getaway when I stayed there in August.
Kinnitty Castle (also stayed there in August) was fantastic, too.
We just returned… As stated, Clontarf is nice. But if you head over to the West coast, I strongly recommend Glenlo Abbey hotel in Galway. It’s 1st class all the way. Make sure to book a dinner in the Orient Express Pullman car on site. It’s pricey, but super nice way to spend an evening.