Help me navigate the world of planning a trip abroad.

I'd second a Eurail pass if the price works out right: it would definitely fit your "not obligated to be somewhere at a certain time" preference a lot better than flying. And trains tend to take you to city centres rather than out-of-town airports, and don't hold you up for hours with security, check-in, etc. On my last flight (Vienna-Rome) I spent 90 minutes in the air and about 6 hours to/from/in airports. Regarding Italian -- English and French should give you a good start. Starting with fluent English and sort-of-OK French, I find I can read most Italian (slowly) and produce bad, ungrammatical but comprehensible sentences. (Understanding it spoken at full speed is far harder, though.)

Hostels ROCK, in my opinion. There's http://www.hihostels.com/dba/hostels-London---London-Central-YHA-018282.en.htm I have been at twice, and it's in a pretty cool neighborhood that is walking-distance to a few nifty things. There is someone at the front desk 24/7, and the staff is usually willing to go above and beyond when it comes to wanting to help. They're also good if you're traveling alone and are worried about being lonely, because you will probably end up in a room with other people, and there's lots of options for conversation (even if it's "can you believe those Spanish girls that just left that brought the two steamer trunks?" or whatever). Hostels that are affiliated with the http://www.hihostels.com/web/hostels.en.htm are usually best in terms of quality and safety.

I would say spend more time in fewer places. You will find this much easier if you can either ship home the larger part of your luggage from the month home or leave it in Rome during your travels-- if you have a lighter bag, you will find it easier and less time-consuming to travel, and you will also be able to take advantage of the cheaper flights where luggage comes at an excruciating premium. It is super easy to get from Rome to London; EasyJet is much better than RyanAir, and even if you fly to Stansted the buses to London aren't that expensive. If you have a week, you could easily do London--Eurostar to Paris--flight to Rome. I would not try to do more than that unless it were a day trip to Versailles or Oxford or something like that, because you'll be strung out on traveling. I would say that Rome is pretty awesome, as is central Italy. (I admit to a strong bias about this.) I would say that hostels and travel will be your primary costs, but an extra three or four days would not add on more than say $230 for sleeping arrangements, so it's probably worth it to take the time to really enjoy the cities you're in. How much money you spend depends a little more on your budget. Hostels are usually pretty awesome; book ahead if you feel strongly about single-sex dorms, and bring a solid padlock or two. AirBnB is also good for short-term visits, so if you were doing three nights in Paris it might be worth it. You can live quite cheaply when it comes to food-- wine and cheese and bread from a market or supermarket! I sometimes pack ziplocs and an extra knife/spoon just in case it makes it easier to do an al fresco thing. Are you interested in music, in bars, in museums...? There are various budget ways of doing this, but knowing more about what you're specifically looking to do will help sort that out.

Why not stay in Italy, or maybe Italy and close environs? Go to Milan, Padua, Venice, Assisi, and obviously, Rome. Maybe add Vienna in, or Budapest, or Ljubliana. It would be both cheaper and in my view better

Also: seconding jetlagaddict on the flights for the Rome-London leg: Ryanair might be cheapest, but they're pretty horrible. I would take EasyJet over them any day, even if it cost a little more. British Airways are better than either, and can be surprisingly cheap to/from Gatwick if you get lucky and book early -- especially if you have hold baggage. Learning some Italian: the Michel Thomas audio course and duolingo.com are working well for me.

I know people coming from the US tend to move through countries quicker, but I could (and have) spent three or more weeks in the south of france at a time. The idea of trying to fit several countries into a week sounds far too rushed for me. In your position, I would pick two weeks, I would fly (if possible) to perpignan or Montpellier or Barcelona, then use the train to make your way back along the Mediterranean coastline slowly, seeing some little places as well as big ones. I personally love Montpellier and the Camargue, Avignon is gorgeous. In Italy there are so many 'can't miss' places - I have spent weeks in Florence, I love Lake Garda and Verona. Rome is worth days by itself. I found public transport easy in Italy, though it was easier to find out about on the internet.

Very helpful. I obviously have a lot more research to do :) Also influencing where I go is friends/family I may be meeting up with while I'm there. If it helps anyone making further suggestions: I'm studying geology, I write fiction, I love art and museums and cemeteries/mausoleums, I like wine (vino/vin), and nature is my friend.