Bob,
Although it will be busy around the Vatican, the rest of Rome will be no more busy than, say, the summer. It's a great time to be in the city and there are many activities - primarily church-driven - all over town.
On Friday night, the Pope will do the Stations of the Cross at the Colosseo (Good Friday), and on Sunday you can see the Pope at Easter Mass. We've been a few times -
here's a report from a couple of years ago! I
Any time you are going to the Vatican during Holy Week it will be crowded.
These tips can help, but I would surely recommend to pre-purchase your tickets on-line for the Vatican Museums, or go with a tour group that skips-the-line. Due to the crowds and closures, this is probably the busiest week of the year for the Museums.
The
Roma Pass is a great idea - not sure where you are staying - but if you are going to two major sites and plan to use the transport system... then yes, get it! The
Roma&Pił Pass, a "provincial version" of the Roma Pass is now again on sale for just €2 more. It covers transport to a larger circle around Rome (including
Tivoli) and gets you into sites "outside" Rome - not sure if you'll have time for that. There are
other discount tickets available, depending on your interests.
The [
buses, metro, and trains will be more crowded. My friends last year had to purchase
1st class tickets from Venice to Rome on Good Friday because 2nd class was sold out. This DOES happen on Holiday Weeks in Italy - not sure where you are coming (or going after) but be aware there may be sold-out trains!
You might check out
www.inromenow.com a few weeks before you come. This is one of many sites that detail upcoming events. On Easter Sunday, after Mass, the city goes very quiet. And of Easter Monday, the day of your departure - many local businesses are also closed.
We've lived next to the Vatican for three years and we actually enjoy the "excitement" of Holy Week. You just have to be selective of when you'll visit Vatican City! Prior to moving to Italy, we often visited Easter week (because my wife is a school teacher and she was on Spring Break) and often flew out on Easter Sunday or Easter Monday. If you're heading
home from FCO, be prepared for a crush at the airport - Good Luck!