I would have the same reservations as you about the area, it wouldn't be somewhere where you'd hang about at night, they'd have to get the Luas to and from anywhere they go. Or a taxi if staying out late. I guess it would depend on their plans.
Yes, that's why I thought that Wynn's might be an option, depending on the price and whether having the Luas track right outside the door ould be noisy. The advantage of Wynn's is that it's just a few minutes' walk from O'Connell Bridge and the start of the tourist trail. I recall from years back that Madigan's across the street did cheap lunches (I can't recall whether it was a carvery) and I think they had live music some nights. Don't know what it's like now.
The Luas is not any noisier than cars and buses, less so in fact. Besides, the hotel is like an amalgamation of several buildings so only the entrance is next to the Luas. I don't know what Wynn's is like these days, or Madigan's, it's so long since I lived in Dublin or visited regularly. I was nervous about the location when I booked the Beresford a few weeks ago but needn't have been, it worked out well and was very convenient for travel both from Heuston and to the airport in the early hours of the morning. Quite a few homeless in the area though, the hotel receptionist said they tend to spend the night close to that area because of the garda station, they feel safer, God love them.
I looked it up. Madigan's is Mooney's now. Do you think there might be a reason that Store St, has one of the biggest Garda stations in the country? Anyway, Miker's relatives will only be here for a couple of days. They'll be fine.