I can’t help with lodging as we stayed at a hotel but even though it’s super touristy, I would highly recommend touring Guinness. I also thought the National Museum and Trinity College were both very worth visiting.
We rented a car when we were there and drove the whole coast but if you are looking for easy day trips with public transportation - we spend a lovely day in Kilkenny. Only 90 minutes from Dublin.
Wicklow Mountains National Park is 45 minutes away. You can take a train or bus but then you’d need to uber/taxi.
If you are looking for an amazing, special dinner, I highly recommend Restaurant Patrick Guilbaud.