It's a decent city to walk around
Definitely do, is a very personal thing, e.g. I couldn't imagine going there, without grazing the food hall at Fallon & Byrne, but that certainly wouldn't be on the radar for most tourists.
Temple bar area is maybe worth a stroll in daytime, but it's a touristy drinking area, which I personally would avoid.
Georges st arcade perhaps a little touristy, but it has some good quirky craft etc. shops
Some nice green areas in the city, that can make a pleasant change. e.g. St Stephens green
Plenty of music pubs, some very authentic, others a little more imported / touristy. It's still a big thing here.
Choose to explore the history / historic sites that take your fancy
If wanting to eat out well, but for modest prices, there was quite a thing for 'early bird' offers around 6-7:30pm, so keep an eye out for them.
Daytrips could absolutely be pre-prepared, but 'in your back pocket' as an option to dip into as the mood takes you. No need to pre-book / ink them into your schedule.