Draft itinerary for Italy late Sept, early Oct. Please help

I did a very similar trip to this one (without the return to Rome). Your itinerary looks very doable and it looks like you gave yourself good time in each location. I don't know how many stops the bus makes from Siena to Florence on Sundays, but I can tell you that a bus stop was directly across from our hotel by shear conicidence. Here are places we stayed (all Rick Steves recommended). Forgive the spelling, I am going by memory.

Rome - Hotel Italia Roma. Decent room, nothing special. Tiny bath. Liked the location. Walkable from train station with our luggage (maybe 4 city blocks) and walkable to most sites in Rome. Closest to the Colleseum. Nice staff.

Siena - Hotel Chisurelli. Great bathroom with a proper shower. Bed was so-so. Cute older building. Nice breakfast in the morning. Our room had a balcony that overlooked the soccer field and we were able to see it from our room which unexpectedly made this a 5 star experience for us! And again, a stone's throw from the bus stop across the road.

Venice - Hotel Campiello (I think, I might be wrong about the name - I can look it up if you can't find it). This was my favorite hotel in Italy. Comfy bed, great modern bathroom. A great shower, but it was a tiny shower. Someone of size might have struggeled in our particular room. Cute place with charachter and super close to St. Marks square. Good breakfast.

I never slept in Florence, just toured it as a day trip.

I did Siena and Florence in May. I strongly recommend Il Salotto di Firenze in Florence (http://www.ilsalottodifirenze.it/). Great location, very nice rooms.

Figure out a way to do the bus between Florence and Siena, not the train, which is slower and less convenient.

I stayed four nights in Siena and took day trips to various Tuscan hill towns. You could do that by bus or by rental car (but if you get a rental car, be sure to get GPS, because when you get back to Siena you'll never find your way). The advantage of a rental car is you'll be able to get to some of the more out-of-the-way hill towns and scenery.

If you want to stay in one of the hill towns as opposed to staying in Siena and doing day trips, my favorites were Pienza and Volterra. But stay in Siena at least a couple of nights.

If you can, I'd consider rearranging the itinerary. Go from Rome to Siena (by bus) first; then Siena to Florence, then Florence to Venice, and then back to Rome. Otherwise, you have a bit of unnecessary backtracking.

Have a great trip!

Your itinerary looks just fine. You have given yourselves plenty of time to see most everything you would like to see.

IMO, you are fine traveling from Rome to Florence and then Florence to Siena. The high-speed takes 1hr.40min from Rome to Florence. The bus takes 3.5hrs plus the time it takes to take the metro from Rome Termini to the Rome Tiburtina train station to get the bus. True that you are backtracking back to Florence from Siena but you won't lose much time overall.

CLICK HERE to see the Sunday train schedule from Florence to Siena. The train station is about a mile downhill from the city but there are usually buses to take you to the city wall. Not sure of the Sunday bus schedule.

The bus system that makes the runs from Florence to Siena is SITA (www.sitabus.it). The runs are severely reduced on Sundays. The bus does take you to the city wall. If the bus is preferable, you might consider traveling to Siena on Friday or Saturday and switching a day with your Florence visit. Note that the SITA bus station is about 1,000 feet from main Florence train station.

On flying early out of Rome-FCO, if you are flying non-stop to the U.S. out of terminal 5, consider being there at least 2.5hrs early for check-in. Often it's less time but on certain days, it can be a zoo. If you are flying to another EU destination to catch your flight, perhaps 2.0hrs will work. It is quite popular to spend your last night in Rome and have your hotel arrange to have a taxi waiting for you in the early hours for the trip to the airport. Fare is fixed at 40Euro but I have seen it a bit higher for the early morning run.