Can u please suggest an itinerary for a max 21 day trip for the following :-
London
Paris
Switzerland
Can either Rome or Barcelona be added to the above places?
I plan to travel in July 2014 and I will be travelling from India.

London 5 days
Eurostar trin to Paris (2 h)
Paris 5 nights
Train to Interlaken, Switzerland for 5 nights in the fantastic Jungfrau Region, to many both the literal and figurative highlight of the Switzerland you've been dreaming about - soaring glacier-girdled peaks overlooking lush valleys - stay in a mountain town like Grindelwald and get intoxicated from the appetizing views from your hotel/guesthouse balcony - take toylike mountain trains or thrilling aerial gondolas to higher elevations, such as to the Jungfraujoch, Europe's highest train station and a world of perpetual snow and ice - you can walk to a glacier!

Then send the rest of the time in Venice (2 nights)

with the final 4 days in Rome!

If going by train - the best for this type of itinerary anyway - check out these IMO superb sources on planning a European rail trip - www.seat61.com; www.ricksteves.com; www.budgeteuropetravel.com. For Eurostar trains London-Paris - www.eurostar.com and early booking, like weeks or months early can result in deep discounted tickets over just showing up and paying full fare - but those tickets are not changeable nor refunded so be sure of your travel dates and times!

Rome and Barcelona are going to be hot.

What mode of travel for Switzerland? Trains? Car rental?

you could fly into rome, spend a few days there, take the train to zurich then on to paris and end the trip in London. I'm sure Barcelona could be added but you'll need to do some research for yourself on what in each city is of interest and then decide how much time to allow. you could look at using overnight trains when possible to maximize time in the various cities vs using a 'day' to travel as well as needing fewer hotel nights as you can sleep on the train. with 21 days and up to 5 cities, you can spend a decent amount of time in each without running yourself ragged or feeling like its been just a taste of each place.

Assuming that the 21 days includes the day you arrive and the day you depart you actually have 19 days. If you wnat to go to 4 places you need to allow 3 days to get from one place to another - meaning you are down to 16 days.

That gives you 4 days each for 4 cities: London, Paris, ONE place in Switz and either Rome or Barcelona. This is a reasonable quick first look at these places. This does not allow for day trips (except in Switz from? I would do Lucerne or Interlaken).

Definitely do not do a RT to and from London - or you will waste a whole day going back. Fly into London and then home from either Rome or Barcelona.

www.swisstravelsystem.com has lots of info on Swiss trains.

"Rome and Barcelona are going to be hot" nandita is flying in from India. I don't think a little heat is an issue.

"Rome and Barcelona are going to be hot" nandita is flying in from India. I don't think a little heat is an issue.>

Well maybe he/she lives in the Himalayas like at Rishikesh or Hardiwar - but yes even the hottest Rome and Barcelona get will be cool for most Indians where they live - especially in August - I spent time in India in August and temps were around 115 F.