1. How did you link to Railsaver? Were you working in the “use a railpass only when it saves money” option?
2. Railsaver.com is the best general recommendation you’re going to get, but it isn’t perfect. It’s based on estimates of standard prices from the distances involved. As you have found, you can often beat it if you’re take advantage of advance purchase and web specials. You must be willing to commit to non-refundable tickets for specific trains (exact date and time) 60 to 90 days in advance from the individual national rail company websites. You must also be able to actually purchase those tickets — not always the case.
3. Trains are relatively cheap in Italy, so a pass might not save money there. However, you probably can not buy tickets from trenitalia.com with a North American credit card so you will most likely not be able to get the best prices. Buying the tickets at the station will easy (if you use the automated kiosks) but will probably be somewhat more expensive than the web prices as you won’t be able to take advantage of web specials.
4. Use the individual national rail company websites (like trenitalia for Italy) to check prices and buy tickets. The links are in a sticky at the top of this forum or under “transport” on the “travel tips” tab. You may not be able to find pricing for international (one country to another) tickets, you may have to go to non-English pages to purchase and you may not be able to actually purchase tickets from these sites. Thus you may not be able to take advantage of web or other advance purchase specials.
5. Unless you’re really lucky finding and buying specials in France and the Benelux countries, a railpass will save you significant money there. All your trips in Italy could effectively be “free” based on your savings in the other countries. As I recall, a 10 day, 3 country pass is exactly the same price as a 10 day France/Benelux pass — thus you can cover your trips in Italy for the difference about $30 a trip — the difference between a 5 day and 10 day pass. You should compare the pass you need for France and Benelux + the costs for your trips in Italy to a 3 country pass for the appropriate number of days.
6. Maybe a 6 or 8 day 3 country pass and some point to point tickets in Italy will be better.

I’ve found train tickets in Italy are really cheap compared to other countries, especially on the (slower) regional trains. You won’t be able to buy them online with an American credit card, but that doesn’t matter- you can buy these cheap tickets at the train station. Unlike other countries (Spain comes to mind), fares advertised online are usually pretty close to what is found at the station; it seems the Italian website doesn’t have as many web specials as others. (Again, Spain has web fares for 60% off for a limited number of seats about 60 days in advance). For 2 separate trips, I’ve relied on point-to-point tickets in Italy, so I wouldn’t be surprised if a railpass didn’t save you any money there.

The SNCF website sometimes has specials that are better than what you’ll get buying in person, even for select journeys in countries other than France. If you book on the website and you have to choose an option for picking up your tickets in France you’ll want to choose the option to pick them up at a ticket window, not an automated machine because the machines only accept European credit cards. You’ll also need to make sure you bring the exact credit card you use to make the purchase or they won’t be able to retrieve your tickets; I found this out the hard way last year.

Thanks for the Responses!

I did use the “use a railpass only when it saves money” option to get my results. I think rather then buying a 10 day railpass, I may buy a 7 day rail pass and buy point-to-point tickets (while there – not online) for most my journeys in Italy. I figure that way I’ll use the pass in France and Belgium, and if there are some more expensive trips iin Italy then I’ll have an extra day or two on my pass to cover those.

I think that’s a good idea. As other people have said, Rail in Italy is dirt cheap and very easy to buy over there. Have a great trip!