My sister and I will be flying into London Dec. 19th. We will stay there for a few days, head to Paris for Christmas, and then Amsterdam for New Year's eve. We are looking for adventure and spontaneous action. We are both in our mid 20's and plan on doing a lot of partying, but are also looking to do some sight seeing. Never been to any of these places before. Traveling by any means, and willing to stay wherever. Looking for advice on:
Must sees, hostels, transportation, etc.

You'll have no shortage of partying opportunities in the London in the week before Christmas. The entire country is permanently pissed for a week.

However it is also my least favourite time of year here. The west end gets invaded by large office parties, who are pissed before they get there and just get more pissed until the tipsy secretaries throw up on your shoes (and the vomit will be purple - it always is).

Also remember that it will be hard to get as restaurant table because of these parties.

However actual night-life venues are, for once, an oasis of calm. They don't let drunks in and are usually pre-bookable.

For cheap but decent hotels check out www.eurocheapo.com

We were in Amsterdam last New Year's eve - pretty amazing. More fireworks than I've ever seen anywhere - really staggering displays for hours in every direction. Can sort of get to be too much of a good thing when the smoke pall hangs over the city for two days afterwards and there are mounds and mounds of red fireworks-paper in heaps all over the city for weeks. ;-> When the canals froze over the end of January there was still fireworks paper in "our" canal making rough spots in the ice! But even though I am a sedate, non-partying 50-something, it was worth seeing. Just don't plan to get any sleep that night.

Last New Year's Eve I heard vague rumblings that some of the more over-the-top fireworks available to john.q.citizen were going to be curtailed somehow, but don't really know if that is true. I think the sheer amount of fireworks is something of an environmental, as well as a personal -safety, no-no. But am not up on the ramifications.

Anyway have fun - I think you will enjoy the spectacle!

The week between Xmas nd New Years is i've been told the very busiest of the year in Amsterdam - book any accommodation NOW or be shut out

Yup a city-wide revelry for the whole week culminating in the bombastic New Years Eve

albertsamuel - look at STA Travel's site (or give them a call)... they specialize in cheap, fun travel for people your age and will probably be the best source of good hostels and first time guides. (You don't need to be a student, but if they ask, say you are and make up a college name.)

Are you on Facebook? I'd recommend looking for Amsterdam, London or travel-related groups where people are posting about the holidays. You can probably meet some people heading to the same places and arrange to meet up when you get there.

I'm high on Let's Go Europe for having great info on hostels and similar low-budget digs - amsterdam has dozens and dozens of such hostels but a few years back when trying to arrange one for my son everything - everything was booked weeks in advance. this is one thing to book now for amsterdam during that week.

A few cheap travel tips:

-If you want to buy guidebooks, look for slightly out of date versions on Amazon.com. We bought a 2008 Portugal guide there for almost nothing.

-Try local foods from street vendors (kababs in London, crepes in Paris)... they're cheap and kind of fun.

-Ask STA Travel for their advice on rail passes. My sister and I bought some a few years ago and they were pointless since we weren't riding enough trains. Also, keep in mind that England and Europe use different passes. Rail travel in England is crazy expensive, so you'll probably want to just stay in London.

More ideas for Paris:

-The Sorbonne (university) is in the 5th arrondissement of Paris and is usually full of people your age. I remember a British pub near the Pantheon that was full of ex-pats, so it could be a good place to meet people. Good, cheap restaurants there, too.

-I'm pretty sure Notre Dame is open on Christmas and it's definitely open on Christmas Eve (and apparently has a pretty cool Christmas eve mass if you'd like that).

-Not sure if this will appeal, but I think Euro Disney is also open Christmas Day.

-A little over 2 hours from Paris, Strausbourg has a big Christmas market (http://www.noel.strasbourg.eu).

-If you feel at all homesick and want to see an American movie, look for movies with the letters V.O. (version original) listed near the showtime. They'll show it in English with French subtitles.

-See the Eiffel Tower in the daytime and look for it later at night when they light it up and make it sparkle. Magic!

-See if you can find a copy of Time Out Paris (at the very least, pick up the London copy and/or look at the site - www.timeout.com)... Time Out publishes a line of magazine guides with good ideas for festivals, clubs, bars, etc.