Wow-what a treasure trove of information. This is the reason I come to this site with my questions and dilemnas. Thank you all for your excellent and quick responses.
To clarify-I am flexible in terms of when I need to return back to Cork so a 2 to 3 day journey is feasible, as is a couple of 2 day 'overnighters'. As someone who has lived most of my life in an older urban area, I find the layers of history, culture, and architecture of such places fascinating. I'll take a rainy afternoon in a Paris museum or a sunny sunday at THE Milan football stadium over a day on a coast anytime although I really do love the coast and the mountains when I do get to them.
I actually like crowds and undergrounds and wide boulevards with giant newstands and food carts and beautiful grand train stations. The car rental idea is a very good one that I will certainly look into but I've had marvelous experiences meeting people on the rails and have seen things from bus windows I would have missed if I needed to watch the road.