Hi,

I have spent a week in Venice and loved it ( both in August 2020- quiet due to covid and December 2022- mostly nice but one day where it rained all day)
I stayed on Guidecca island ( at the hilton ) about a 15min public vaporetto to St Mark;s square
It is nice just to wander around the sestieres of venice ( quarters) away from the major sites and you will find something interesting. Lots of bridges and small squares including a three arch bridge and a bridge with no handrails

The Ponte d'Academia is beautiful and you can get beautiful photos
Riatlo bridge
I loved the eastern part of venice ( Sant' Elena) , The Giardini and San pietro island
The Salute basillica and San Giorgio Maggiore are beautiful
You could probably do a lot of major sites at a reasonable pace in 2days ( 1 day you would be dashing around)
Burano ( beautiful coloured houses are worth a visit) and Murano are worth a visit -maybe not with only 2 days

Regards

TBS

Also 2 days in Rome is not enough either so I think you may need to carefully plan which sites you want to see