I was in Rome last week for a couple of days on business.
Take the train from the airport into the city. 12 Euros each, and half the time and price of a taxi.
Try the open top, hop on, hop off bus tour. About half a dozen different companies operating, and I think they all do a similar route.
Good value, and you get to see everything at your own pace.
Restaurants everywhere, but quite pricey.
Queues at the Vatican were ridiculous, but you’ll be approached by guides offering tickets to jump the them. Don’t know if they’re genuine.
It’s a beautiful city, you can’t fail to enjoy it.