Which Train Passes/What airline?

Don't get a pass, you shouldn't need it really. Here's what I might suggest:

Fly nonstop to London on British Air or NW (Heathrow) and back from Rome.
Chunnell train from London to Paris.
TGV from Paris to Nice.
Train from Nice to Barcelona.
Train from Barcelona to Madrid.
Flight from Madrid to Rome on a budget airline.

However, I think personally you are trying to do too much in this short period of time. I might cut it down to say London, Paris and Nice rather than all six cities.

I agree with the others that you need to scale things back a bit. Otherwise you'll spend more of your time "getting there" than you will "being there."

However, here are my transportation recommendations for the routes you gave.

London-Paris: Eurostar.

Paris-Nice: Direct night train (11 hours) or daytime direct TGV (5 1/2 hours) or easyJet (budget airline)from either Orly or CDG (90 minutes). Personally I'd pick the night train because it saves the cost of a night in a hotel, gives more daylight hours for sightseeing, and leaves less of a carbon footprint than flying.

Nice-Barcelona: It's too long a train ride with too many changes for too much money. To save both time and money, fly Vueling (budget airline).

Barcelona-Madrid: Take the train or fly Vueling.

Madrid-Rome: Fly Vueling or Air Europa.

Now what cities are you going to cut out?

Thanks for all the advice so far! I guess I could cut out all of Spain. I wouldn't feel right being so close to rome and not making the jaunt over. Cutting out a whole country would mean less hotel reservations, and fewer tickets to buy!

Does Paris, Nice, Rome sound like a better idea for a 14 day trip?

Brett: Nice job on simplifying your trip, you're improving the quality of the experience you and your travel partners will have. But instead of the 3 cities of Paris, Nice, and Rome, I'd suggest the 3 cities of London, Paris, and Rome--the three great cities of Europe. But London is an expensive city for accommodations, and everything else, so some would advise against it based on cost. If you want some beach time, then Nice makes sense.

Brett,
Paris, NIce and Rome sounds good. You'll have a nice time. Going to the French Riviera in the middle of your trip will be a nice little break from the sites of Paris and Rome. May I suggest you stay in Villefranch SurMer instead of Nice. Villefranche is only a 5 kilometer and easy train ride from Nice. It's beautiful abd slow paced. I went a few years ago - in late May, and never wanted to leave. Hotel De La Darse is a nice, budget hotel with amazing views of the harbor. It is right on the old harbor. Harbor view rooms with a small balcony are very reasonable. From Villefranche, you can easily explore Nice, Antibes, Monaco, Eze la Village, etc by train, bus or car. I would fly into Paris and out of Rome - easy airport connections to the center of the city. I would fly a budget carrier from Nice to Rome. Regardless where you end up going - have a great vacation!