One hotel/ City for sightseeing in Rome ,Florence and Venice.

It is foolish to stay in one place and try to see all three. A quick look at a map will show you that Florence is between Rome and Venice. so if you're determined to do this anyway, stay there. But don't. Fly into Rome and out of Venice or vice versa.

It is more difficult to move a group of five, but daytripping to Roma or Venezia won't do justice to those cities. How many nights on the ground do you have? If eight nights, I would stay in Venezia for two, Firenze and Roma for three each.

Would suggest you do like Zoé
said
2 nights Venice
3 nights Florence
3 nights Rome

Or 4 nights in Florence
4 nights in Rome
And do Venice another Time.

Day 1. Arrive Venice (2)
Day 3. Late train to Florence (2)
Day 5. Late train to Rome (3)
Day 8. Depart Rome

David is giving you good advice. It will give you a good sample of Italy in very short time. It would be nice if you had 2 or 3 more days.

Yep. It is foolish.

However you were smart enough to come here and ask, and David in Brisbane gave you the perfect solution.

I certainly agree with the above advice. Also wanted to mention that the Venice Carnival will take place Feb. 11-28, so if you want to be there during that time, it would be advisable to secure lodgings ASAP.

We are 6 adults going to Rome for 8 days, leaving the 9th also in February. We decided to stay In Rome the entire time and day trip to Orvieto and Pompeii.

The reasons were a few
- no changing hotels
- no transportation problems
- no wasting time moving from city to city
- will really get to see Rome without rushing around too much
- not having to move 6 people around
- each couple can go on their own if need be and we can meet up for dinner

My Husband and I have done "group" travel before and when this trip grew from us to 3 couples we set the ground rules. Staying in one city is so much easier and since I do all the planning and try to make my vacation headache free, one city it is.

Also wanted to mention that the Venice Carnival will take place Feb. 11-28

Hot tip. See if you can be there Sat & Sun, the 11th & 12th. This will be the Grand Opening weekend and it will not be that busy, hotel wise. Saturday night will be a "Float" parade on the Canale di Cannaregio near the train station. Not to be missed. https://www.youtube.com/watch?v=t5M6H1TbmX8

Sunday afternoon, another parade of people in costume rowing traditional and nontraditional Venetian watercraft. My fave, the long canoe paddled by the ladies of the Mestre Lionesses. And get this, free food, provided by local service groups. Ok, its served in paper plates with plastic forks, but what the heck, its free.
https://www.youtube.com/watch?v=9-rFGucrn1U

If 7 nights, I'd go with David's itinerary.
If 8 nights, go with Zoe's.

But honestly if you can push for even one more night, I'd try and do that...especially if all you currently have is 7 nights IN Italy itself. You airfare is the largest single expense that you'll have - and the longest time you'll be stuck in transit - so it's worth every cent/vacation day to stay as long as you can. Depending on how how long your flight is and how well you manage jet lag, your arrival day may be a blur.

Just restating what is above. Staying in one place had advantages and works with places such as Barbara describes with Rome but that is much different than the 3 big cities you are planning.
You will need/want to change hotels to see these 3 places.

I would give Rome a minimum of 3 nights, any of the above combos can work.