Traveling in May and looking for ideas

Hi lads, I'll be visiting Dublin in mid-May. My wife is attending a work conference so I'll be mostly entertaining myself during the day.

Get in on a red eye on Monday morning and leave on Friday. Would it be crazy to book day trips for all three days Tuesday through Thursday? Thinking of:

• Belfast / Giants Causeway

• Kilkenny, Wicklow Mountains, Glendalough

• Howth

Got some decision paralysis so any input is appreciated. Howth seems like it's the closest and easiest one, and probably wouldn't take up the whole day.