Well Uppercross House is a 70s B&B masquerading as an hotel. Grossly overpriced at €220 a night (extra if you dont pay at the time of booking with booking.com). In fairness, given that part of the B&B would appear to be given over to immigrants, the rooms that are left are charged at a premium rate. The staff were pleasant and helpful.
You can easily get a bus into Dublin from Rathmines.