Moving this on from a treatise on the linguistic conventions of Europe...

Looks like a nice itinerary. You haven't made the classic mistake of 10 cities in 9 days ^. Without knowing your interests it's difficult to suggest anything specific, but here are some thoughts.

- It's very city based. Have you thought of spending some time in the mountains, or on the coast? I'd definitely recommend getting out of the capital in at least one of the countries you visit.

- You could take the night train from Paris to Munich (or Berlin). They can be very comfortable, as long as you don't try to do two nights in a row.

- Berlin vs Munich - I've visited them both, and would happily spend time in both again. Berlin probably edges it if I had to choose because there's so much history there. But Munich might make a nice base for a dash up to the Alps.

- The Alps themselves are a wonderful playground can be approached in a zillion ways, depending on what you want to do there (walk, climb, 'extreme sports', cable car up to look, scenic flight, nature walk, driving or cycling tour, skiing (just, if the snow's still there at the end of April), and a million more). If you let us know what appeals in the Alps, I'm sure someone can suggest a base, and how it might fit in with the rest of your itinerary.

- Dublin has never done it for me. Nice for a day and a night, but after that I would rather spend some time on the west coast. You can pick up a hire car cheaply enough in Dublin.

You may have found it already, but http://www.seat61.com/ is the definitive source for anything European Rail related.