I think your pace is reasonable, so I wouldn’t worry too much about cutting. While I fully agree with luv-the-beach that visiting only big cities is a mistake, if that’s what you want to do, then it’s your time and money. All of your cities are fine, but some things to think about as you plan….

Copenhagen: it’s a beautiful city, but it’s very expensive (especially for partying) and much more “out of the way” than you might think. You’d could easily blow a day getting there and another day getting to your next destination. Flying would help a little, but any flight takes nearly 5 hours (which can blow a whole day) when you figure getting to/from airports and 2 hour check-in/security time plus you may find the flight options to/from Copenhagen very expensive.
Zurich: It’s not in the alps, it’s well up on the list of most expensive cities in Europe and I (others disagree) don’t think it’s a great visit. However, it’s a major transportation hub, so “easy” and it isn’t the capital… I would pick someplace much less urban if you want to experience Switzerland.
Dublin: a decent city, but in many ways “just another city” for me. I wouldn’t spend the time and money if you don’t have a few days to explore a bit of Ireland or at least take a couple of day trips from Dublin.
Vienna: I much prefer nearby Bratislava — cheaper, friendlier (full of kids from Vienna taking advantage of the cheaper partying on weekends) and I think more interesting. However, Vienna is a major transportation hub, so easier and with more options for flights, overnight trains, fast connections to other major cities.

Thanks so much old lady. Would it be better to go to Lucerne instead of Zurich and only use it as a train hub? My friends and I were thinking that we should go Copenhagen and then to Berlin and go down from there, and Lucerne to Paris. Would that cut down travel time? And in regards to how expensive it is, we’re on a budget but not broke, so I think we’d be ok. One last question, should we make it a round trip from London by flying from Copenhagen from there and getting bak through Paris? Thank you do much

Travel time is going to be an issue for this trip regardless of how you order the cities. Check train schedules at http://reiseauskunft…? Use www.whichbudget.com to see which low fare airlines fly which routes and to get an idea of likely cost and scheduling and then plot out the portions of your trip that are eaten up with travel.

I would not do a roundtip from London to Copenhagen unless the other options were too expensive as it will likely waste an extra day. Check transatlantic flight prices for several combinations of arrival and departure cities.

so total change of plan. Going for a shorter trip (about 20 days)
Fly to London
London 4days
Paris 4 days
Berlin 2 days
Munich 2 days
Rome 3-4 days
Florence 3 days
Cinque Terre 2 days
Back to Rome for the flight home

Too much in a shorter time?

Looks good to me, but why go Munich to Rome and not Munich to Florence so you don’t wind up backtracking to Rome?

I was just going to post the same comment as Agustine. Munich-Florence is 7 1/2 hours by train. Munich-Rome is two hours longer. Look at taking the City Night Line train from Munich to Florence to save some time by traveling overnight and avoiding the backtracking of a second visit to Rome to catch your flight.

Great! Thanks. What should I do for rail passes. Should I get a pass or just pay individual fares?

1. Buy the Eurostar (London to Paris) ticket as soon as you’re sure of the date at www.eurostar.com Eurostar isn’t covered by rail pass.
2. If you’re willing to commit to non-refundable tickets for specific dates and times, use the French and German rail company websites to buy the tickets to get as far as Florence. Buy up to 60 days in advance to get the best deals. Buy tickets at the station as you go in Italy.

great