Rome, Paris, London, or Amsterdam in January?

None of these cities are subject to frequent heavy snowfall. Actually, relevant snowfall in Rome is not even an yearly event, when it happens it is news in Italy. All these cities have plenty of nightlife options to suit different tastes and wallets. Just beware of the ticket to Dublin + Ryanair plan: if by any reason your preceding flight is late, Ryanair won't do anything to accommodate you, and you will lose your ticket and be forced to buy a last-minute high-cost new ticket to reach your destination. The opposite happens on your return ticket to US. If you want to fly to Amsterdam, or Paris (or else), buy a ticket to that city. It is often less expensive if you factor the need for one night in Dublin "just in case" your incoming flight is late (and the opposite for return trip)

I agree with Andre that, particularly in winter, you don't want to be flying on separate tickets. Since that's low season, you shouldn't have to pay too much more to fly right to your destination, all on one ticket. This way, the airline is responsible if there is a missed connection due to weather or flight delays (they'll usually put you on the next flight). If you're on separate tickets, you are responsible both logistically (the airlines won't help you) and financially (and a last minute ticket back to the US could cost more than the whole rest of your vacation). To research nightlife options for college students, you can look at places like the Thorn Tree forum or Time Out. Neither Rick's books nor this forum will be of much help in that area. As large cities, all four of your cities will have lots of opportunities. One factor to consider is language; the nightlife in Amsterdam and London (and for that matter, Dublin) is going to more hospitable to English-only speakers.

I agree, you should spend your first night and your last night in the city you are flying into/out of. If you want to spend time in that city, it's great. If not, you have to factor in the cost of getting to and from the airport to a cheap hotel (the ones near the airport aren't usually). Then decide if it's worth saving X dollars and losing as much as two days of sightseeing. All 4 cities are lovely after dark, with floodlit buildings and monuments. You'll have a good chance of sunshine and warmth in Rome. I was in Rome last year in February in the snow - the first in at least 20 years, they said. So the chances of snow are pretty low for the next 20 years or so. I too think you'll find nightlife in any of these cities if you do a little research. What are you going to do during the day? If you want to sightsee, Amsterdam probably has the least to offer for a 10-day stay. There's much more to see and do in Rome, and even more in Paris and London.

Thanks everyone for the well-informed replies! I'm definitely going to look into purchasing tickets directly to Rome now. Prices are in the lower $1000 range to Rome which is a bit much but maybe I just need to wait a little longer and keep watching the prices. Does anyone have any experience with RyanAir/EasyJet/etc. though? I'm curious as to how reliable those airlines are.

I've used Ryan air. Think city bus with wings; that applies to some passenger decorum also. But the flight attendants were good about controlling that. We hadn't left the ground yet and they were very clear with the problem passengers that they either settled down, quietly, or they would be removed. The overall experience was OK. Got me where I wanted to go, cheaply. But you need to follow their rules to the letter. Otherwise, you'll pay high fees. which will undo the savings. Also, you need to book early to take advantage of the savings. I've flown the same route with Air France and Ryan Air. If I were booking late, the savings would be small and not worth it; I'd take Air France. But with an early booking, saving more than 60% was worth the hassle of Ryan Air.

Rome would probably be your best bet weather-wise, but I would also consider a London-Paris option with 10 days. You could split your time between the cities, and they are a relatively inexpensive train ride away from each other (if you buy early enough). However, London would most likely be the most expensive city of the bunch, so that may be a factor. On the other hand, flights there are usually the inexpensive ones. I really think you need to create a pros-cons chart with each city (and include non-tangible categories as well) and see which one comes out on top.

Careful of false economy.. For instance if you use Ryanair to fly to Paris they do not use the main two airports but they use Beauvais.. which is almost 100 kms from Paris itself and requires you to take train AND bus to get in ,and 1.5 hrs.. maybe longer in winter when less frequent buses.. I would strongly advise using Easyjet or Vueling , I have used both, they use main airports. From Seattle you have the option of flying out of Vancouver BC.. using airtransat.. Also remember back tracking cost money.. its better to fly in to one city and out of another back home ( if you plan on staying in more then one place). Amsterdam would be fun for young folks, but yes, cold and rainy, Berlin would be cold, and maybe snowy, but its definately a fun city for young folks, I think for me I would stay south , sure won't be hot or even warm anywhere but at least not butt freezing .. lol I Think Rome or Barcelona would be good choices.. and of course I totally love Paris so that would be my first choice! Or fly into London, take Eurostar to Paris ( this can be very cheap, like 40 euros ) and fly out of Paris,, remember you are not pricing two one ways, you are pricing a "multi destination" or
"open jaw" ticket when checking out booking sites.. and even now its a bit early to get best prices but keep looking then you will know a deal when one pops up.

To expand on Pat's excellent post, any flights within Europe and any trains between countries (and some, but not all, trains within a country) should be bought in advance to get reasonable prices. If you wait until the last minute, you'll pay a fortune. Since budget is important to you, be sure you find out when the tickets go on sale, and book right away to snag the discounts.