Ireland...?

Anyone? Going there for my 1st time. My FH's 3rd. What are the must sees and must avoids? He wants me to select since he's been there already but he's excited to go back. I've always wanted to go and I have an incredible opportunity for this that I can't turn down.

TIA!

It was beautiful. My only suggestion is to avoid any tours on buses! We went and hopped from place to place, which was great, but I missed so much scenery and history explained because the driving put me to sleep