Do i need buy train passes in advance or are they similar in price in europe as they are on-line?
Where are your origination and destination points. Lots of variables depending on your answer. Europe is a big place.
We are on our honeymoon. WE will be arriving in London for three days and then taking the "train" to Paris for 4 days. From there we will be back to London where we will fly to Rome. Wile in ROme, I'd like to do as many day trips as possible, Florence, Naples, Pompei, Venice, Sorretno...what do you recommend?
For London to Paris, you may want to book online in advance for this ticket. This train can get busy. There are some nice discounts if you book in advance.
Once you get to Rome, you can easily buy your tickets to Florence, Venice and Naples at any rail station. Use www.trenitalia.com to plan your journeys and to write down the trains and dates you want. Don't look farther out than early June as Trenitalia will be updating their site in mid-June and looking farther out than that is sketchy. Unfortunately, Trenitalia does not accept most American credit cards so travel planning is about all you can do.
Please don't consider a Eurail pass in Italy for 3 reasons: 1) P2P is almost always less expensive than the Eurail pass in Italy. 2) On your runs to Florence, Venice and Naples, you will most likely be on Eurostar-class trains as those are highly-popular high-speed runs. Trenitalia charges a supplemental fee of 15E-20E for each run that includes a Eurostar-class train. I see six such runs for openers for your itinerary (unless you want to be on slower trains). 3) The private Circumvesuviana train from Naples to Pompei and Sorrento does not accept the Eurail pass.
"similar in price in Europe as they are on-line?"
I guess the question is "what on-line"? If you find on-line prices on one of the European rail company websites, like Bahn.de or trenitalia.com, the "full" prices on these sites are exactly the same as the price at the counter over there (some online fares might even be less). If you find a price on a stateside website, like RailEurope, those online prices will be much higher than what you would get over there.
This may be a silly question....but why are you returning to London from Paris, then flying to Rome? Why not just catch a flight from Paris to Rome to maximize your time and save yourself some $$$?
Thanks for the great advice. A big help.