Question about train travel in Italy?

My fiance and I will be travelling to Italy for our Honeymoon in June. We will be travelling from Rome to Florence, Florence to Venice, Venice to Sorrento and Sorrento to Rome, all on different days. We have looked into getting a EuroRail supersaver pass that entitles us to 3 days of unlimited travel, also purchasing an extra day. Altogether this will run about $450. Is this the best, most cost effective way to travel? Their website is difficult to understand, do we still need to pay extra for tickets? How do we know if we need reservations?

Get in touch with a professional

Are you sure three or four days are enough for visiting all those cities...? From Venice to Naples it takes near 7 hours, for instance (and still more than one hour to Sorrento).
Anyway, booking from Trenitalia and Circumvesuviana http://www.trenitalia.com/en/index.html http://en.wikipedia.org/wiki/Circumvesuviana
should cost you near those 450$, all included.
Take a look at Trenitalia website and make your reckoning.
Since your stay time is narrow, I suggest you to book in advance, anyway.

This is the link to Eurail for Italy
http://www.eurail.com/
As far I can see rates are lower than yours and you can cover also 4 and 5 days of unlimited travelling.However I'm guessing how is possible for you to visit the 4 towns in 4 days...!!Also I don't know why you've decided for one day trip Venice to Sorrento but this will be really a long trip. If you're landing in Rome I would suggest a daytrip from there to Sorrento.
When you're back at Rome (or direct from Sorrento) you may go to Florence and then to Venice. Last daytrip should be from Venice to Rome if you're flying back from there.
Here is Trenitalia (Italian railways system) website for time tables http://www.trenitalia.com/en/index.html
Here you can check also about reservation. Pls note that seat reservation is always mandatory on Eurostar (ES) and Intercity (IC) trains that are also the fastest (and the one I presume you'll be using for yr trips).
I guess by scrolling all the arguments of above 2 links you'll find any further answer to yr possible questions.
Otherwise feel free emailing me for any clarification since I'm a frequent train traveller (even if obviously I can't travel with the Eurail being Italian).