how long to visit each place

This is a tricky question. If you're into visiting museums than you could easily spend a week in each. How many days is the total trip going to be? From my personal experience I'd say London and Rome at least 4 days, Paris, Berlin, Munich at least 3 days, Amsterdam, Prague, Milan, Barcelona at least 2 full days...

brittany, my preferences for length of stay in each city would be:

London- 4-5 days minimum

Paris- 4-5 days minimum

Rome- 4-5 days minimum

Milan - I would probably drop Milan in favour of Florence, but I guess would depend on what you want to see? 2-3 days?

Prague - 3-4 days

Munich - 3-4 days

Berlin - 3-4 days

Amsterdam - 2-3 days

Athens - 2-3 days max.

Barcelona - 3-4 days

Of course the time spent in each location will depend to some extent on what sites you want to see? Also whichever city you're starting in, you might want to add an extra day as you'll lose the first day in flight and time zone changes.

It would help if you could provide some further details on your travel plans. If this is your first trip, I'd highly recommend reading Rick's Europe Through The Back door before you get too far in your planning. Finally, you can get good tips & Itinerary info. at pretravel.proboards1.com if you want other opinions.

Cheers!

brittany, a bit more to add....

Rather than Milan, you could also consider a few days at either Lago di Como (Varenna is my favourite, with day trips to Bellagio and other spots) or the Cinque Terre (west of Pisa).

I would purchase a few guide books. I use: Frommer's; Steves; Lonely Planet; and DK. Each will give you a different perspective on the same destinations. Once you do some research on what interests you, you will be able better to determine the length of time at each destination.

Brittany, How long is your trip in total?? This would help. Also , what sort of budget are you on, some cities are more expensive ,therefore perhaps worth spending less time in so you can stretch your travel dollar.
Athens sucks, go for a day or two ,then ,get out to the WONDERFUL islands. Santorini,Mykonos, Paros. all wonderful for a first time visit. . When I was young and my friend and I did a few months in Europe we found the Greek islands to be our favorite destination after Switzerland and Paris.
Paris is worth 5 days minimum, assuming you do a daytrip to Versailles( a " must do").
London is expensive, and the pound is worth twice our dollar plus, so a shorter stay there perhaps.
Amsterdam is worth 2-3 days.
Rome 4-5 days( and perhaps a day trip there too).
Never been to Milan or Prague. I would love to do Prague, but have heard nothing that thrills me about Milan.
Alot of this is based on personal tastes too, so everyones opinions will be different.
And trip duration.

Brittany,

I think people answer this question based on age, travel style and personality. It depends on what you like. For my family 4-5 days in any city is too long. 3 days in London is great! 3 days in Rome is too much. 3 days in Munich is too much unless you are doing side trips to Dachau or Fussen. 2 days in Amsterdam is plenty. The only place we have stayed 4+ days is Lauterbrunnen Switzerland, and we were quite sad to be leaving there.

When planning my trips I take to heart what Rick says in the "planning your time" area before every city / area. I also look to see how many of the sights in that city really interest me and go from there.

Hello Brittany. I recommend :
London = 3 whole days.
Paris = 2 whole days.
Rome = 2 whole days (maximum).
Prague = 2 whole days.
Munich = 2 whole days (maximum).
Berlin = 2 whole days.
Amsterdam = 1 whole day.
Athens = 2 days (maximum).
Barcelona = 1 day.
I do not recommend being a tourist in Milan. But, flying to (or from) the Malpensa airport of Milan is convenient for some people. I guess : being a tourist in Milan could be a pleasant experience for persons having overnight accomodations there in a 3-Star hotel, or in a good business class hotel. And eating in the best restaurants. And traveling from a hotel to a museum in a luxury limousine driven by a chauffeur. And relaxing in a warm water jaccuzi or pool, and getting a massage, for rehabilitation after experiencing stress in that awful city.

We spent 2 weeks in London in 2004 and 2 more weeks
there in 2006 without repeating anything but the
British Museum. It all depends on you travel style
and what you want to see. Other cities you mention
that we have visited: I would give Rome a week, 4-5 days in Prague and just 2-3 days to Athens.

thanks everyone.. to answer any of your questions.. i am planning on doing all of eastern europe/mediteranean in about 4 months. And im not really on a limited budget of any sort. Thanks for everyones inputs, they help alot.