re: Europe

Really you could do 5 days at any of the places you mentioned. So much history, scenery, and things to do that you would enjoy it. Now if you're the type you just want to say you've been there done that then you want want to break it up to multiple cities or see somewhere like London or Paris

5 days to do ireland will require much and tiring hustle. either extend your trip or just do london with a couple of side trips. can do paris with side trips too. i prefer france and especially normandy.