1st trip to Italy but based out of Vicenza area

In my opinion the only "supposed" to is what you want to do. I knew that I would visit Italy more than once so I felt no need to try and see as many cities as possible. The first trip was a family trip and we decided how many cities etc together and then I put together our itinerary. Padova is also very close to Vicenza .

With only 8-9 days, sadly you don't have enough time to see all you want to see. I have had the luxury of spending one month travelling Italy north of Rome and I stil feel like i missed stuff. Just accept the fact that you can't see all that Italy has to offer and be content with what you do see.
Vicenza is worth a day and Verona is nice for a day trip. Venice could use 2-3 days, especially if you can stay in Venice proper, so you can enjoy the city in the evening, when most of the day trippers have gone. Florence is worth another 2-3 days, depending on how much you enjoy art museums. Rome has so much to see, that you need at least 4 days.
My point is that you have to prioritize, but remember that there are no 'must sees', only you can decide.

Tina, I generally agree with the others, that with limited time you should limit yourselves to the Venice to Florence corridor. May is a great month to be there. Should be lovely weather, not too hot, and not too crowded. I don't know if you will actually be staying at your sister's home in Vicenza or not. If so, you might take one or two day trips into Venice, free of hotel bills and luggage. But if you do, be sure to go very early morning and/or stay late into the evening, as the very best times to visit Venice are early morning and evening, when things are quieter and the (other) day trippers are not present. Padua and Verona are also easy day trips. Then, two, three or even four days in Florence, staying someplace right in town. Florence is a walk-almost-everywhere type of town. Rome is too far, and takes too long to really see even briefly, for a trip of just 8 or 9 days, in my humble. With an extra day in Florence, you could take a day trip to Siena or some other Tuscan hill town, or even one of the day tours which stops in a couple of popular hill towns, a winery for lunch, and takes you through the wonderful Tuscan countryside.

The first Regionale train to Venice is at 5:05 am and the last train back to Vicenza is at 10:35 pm. Between 7 am and 9 pm trains are basically 2 trains every hour each way.
Verona, Padua, Ferrara, Ravenna, Bologna are other day trip possibilities. Dolomite mountains are nearby as well, but maybe an overnight trip due to travel times.

I see this just a little differently.

You said that this is your first trip - for both of you - to Italy... you didn't say that this is your first trip to Europe.

So I'm going to run with you are experienced travelers and see what you think of this.

Once you have visited Italy you may not want to go anywhere else for your holidays again, so you can chop the country up a bit and do a different section each time.

Nobody will condemn you if you visit central and southern Italy on future trips. That's what I've done.

Will you have access to your sister's car?

There are soooo many things to do just in a short distance from Vicenza that you could be there a week and barely scratch the surface. I had a jasmine covered apartment there for a week and wished I'd had two.

Vicenza is one of my favourite Italian cities (behind Venice and Rome, but not far behind) and the Veneto area and nearby is just chock full.

Just for a few -

A life sized chess board where citizens don costumes and act out the match.

A painted covered bridge in the home of Grappa.

Walled towns like Soave (where Soave wine comes from).

The building that Monticello was modelled on.

Dozens upon dozens of Palladian masterpieces scattered through the countryside.

A Gipsoteca where Canova worked and is buried. Plaster copies of most of his work is available for view.

A covered walkway up the hill from town all the way to a pilgrimage church.

Great jazz music.

Excellent gelato.

Hot baths.

and I've just scratched the surface to give you a taster - all these and much more is within about a 25 mile radius of Vicenza.

Then Verona, Padova (Padua), and Venezia (Venice) are just a short short train ride away; Ravenna, Modena, Parma, Bologna, Trieste, Bolzano all just a little bit further, and then Florence. I think you don't have time for Rome, you barely have time for Florence.

Being in or near Vicenza might give you more quality time with your sister, too.

What do you think?

Having spent several days on several trips in that area, I agree with Nigel; you may never want/need to leave the Vicenza area. However, if it's your first trip to Italy, you are probably chomping at the bit to explore further afield. Follow your instincts when you say that you think Rome is too much. It would be a good idea to stay closer to Vicenza, perhaps explore as far as Florence. But, as Nigel mentions, no need to leave the Vicenza area to enjoy fantastic wines. Also, if you enjoy visiting beautiful villas, for example Villa Pisani (near Padova) with a huge area outside the villa to stroll through including a hedge maze, not to mention the interior of the villa itself, you will find lots to explore near Vicenza and Padova.

Nigel, I think I need the contact info on that jasmine-covered apartment.

I'm happy to share that, Laurel. It would be a good choice for many.

Bob and Jenny's Bed and Breakfast at http://www.bed-breakfast-italy.com/
Great folks, €60 a night, convenient, even has parking (slightly off premises), not far to a great caffé bar, close to a small neighborhood pizzeria, which is across from a large Despar.

We loved it there. Now we have a (dramatically less impressive) large arch of jasmine in our own garden, inspired by that week in Vicenza with Bob and Jenny.

I would refrain from going to Florence, although I love it and have my house there but were I you, I would concentrate on
- Vicenza (Palladio architect has designed so many beautiful estates in the area and it is worth taking a Palladio tour), As you have your sister there you will also need some time with her and she might not be able to be with you during the day (work for instance) and you might like to spend some evenings with her and the following morning, not get up at 5 am in the morning to travel to Florence or Rome
I therefore suggest 2 full days (3 nights) to visit Vicenza and neighborhoods plus half a day with your friends and/or family.
Venice would need at least 3 full days and the rest would go to Verona and maybe Parma. Ravenna may also be interesting but choose only one of them.
Also I believe you will arrive or leave back home in/from Venice, so it would make sense to put the three days for Venice altogether and not going first and last days in Vicenza. Your sister will understand.
The other cities I mentioned could be day trips from Vicenza.

Do Florence, Tuscany and Umbria - Rome in another 2-3 weeks tour.

Bye for now.

Françoise

Thank you to everyone for the input/advice. I have definitely decided not to include Rome on this trip. Fortunately my sister will be off work during our visit and yes we will have access to her car (we will be all together). I have decided to divide my trip into the Vicezna area (including Venice) and Florence area. It sounds like there is so much to do in both regions. Yes, I have been to Europe before, just not Italy although my husband lived in Italy for 3 years in the past. We realize how quickly 8-9 days can pass on trip to Europe! I am currently deciding how much time to spend in each area. I am thinking 5 days in Vicenza region, including 2 in Venice (also includes that 1st day of jet lag/adjustment). And 4 days exploring some regions in and around Florence. Thanks again everyone. Your help is much appreciated.