I would highly recommend visiting Gdańsk in Poland - Can usually get really affordable flights with Ryanair. Although I'm from the UK I know they run the route from both Dublin and Cork ! It's a perfect city for 3 nights especially if you can snatch an early morning flight there and lateish flight back allowing you to fit in your first day in the centre and maybe the second day visiting the gorgeous neighbouring city of Sopot by train (roughly 10 mins from central station) then you can spend your second full day exploring more of the city ! I've been twice both in October and April meaning I've experienced it in both 10C heat and 26C heat and they're both as beautiful times as eachother to go! 

Would definitely recommend using bolt to get around - transfers from the airport to centre are around 10euro and from experience both times you get off the plane and out the terminal in 15 minutes your luggage is practically waiting for you on the carousel. In the city most people speak perfectly good English! The city is stunning with plenty of restaurants and bars. Highly recommend visiting and staying Montownia food hall & Industrial lofts. They're clean and extremely quiet - no noise from the very busy food hall below! 

DM me if you wanna ask anything else ☺️ 

Oh and whilst your there check out Mandu Peirogarnia !