I’ll be the dissenting voice on Temple Bar: I would avoid it at all costs. I find it loud and touristy and kind of depressing.
One of the things I love to do when staying in Dublin is take the DART to Sandycove (to the south, for the beach and Forty Foot) or to Howth (to the north, to hike the Cliff Walk)—both so gorgeous and accessible from the city.
Culturally, we’ve enjoyed the Royal Hibernian Academy, which is an art museum that is small enough to cover in a few hours. And there’s a fantastic walking tour of Dublin led by Trinity College history graduate students: Dublin Historical Walking Tour – Lost in the Right Direction .
Agree with the Books Upstairs rec. Charming store.
For accommodations, I’ve had good luck with https://fivestar.ie and https://uniqueirishhomes.ie.
Have fun!