hey hey sip4270
when is this trip and how many people, are you traveling by train or car?
drop CT and add to venice. lots to do & see in venice and you are not giving it enough time. how many days in rome and how many days in florence?
check -in times are 3-4pm and check-out times are 10-11am, take that into consideration. you do not want to be roaming around with luggage, usually your hotel will have luggage storage until check in. do you have hotels booked in rome and florence with your transportation figured out?
venice is a place in itself and beautiful getting lost, only issue i have is so many flights to USA are so so early morning, call it "dark thirty"! we reserve and take a private water taxi$$$ (motoscafivenezia.it). many people like landing in venice, getting over "jetlag" it's real then trains south to florence or rome, plus FCO has many options to fly back home.
what are your plans, activities, attractions hoping to see. make sure you rersve tickets at their own website, day/time stamped. people here are the forum are great to give you options to help you out, we are only volunteers that have traveled alot making lots of mistakes, make holiday simplier and be prepared. you can research, agree or disagree, it's up to you. don't be cramming to see everything, it won't happen, enjoy what you can, stop and smell the bolognese and cappucino, taste gelato and great pastry. keep asking questions. enjoy and have fun
aloha