Best site for booking apartments and travel itinerary

We used airbnb for all those places (plus Sorrento and a place in the Tuscan countryside). Our trip should be completed in late October and I'll try to report back on how the places were. I have used airbnb in many parts of the US and have never had a problem. Pay attention to the reviews there in making your selections. Also, define clearly what you want (there are drop downs for amenities like wifi, washer, etc.) and you can use the map to narrow down your neighborhoods as well.

Homeaway anfd VRBO are affiliated. The former mostly has places managed by pros. The latter's properties are mostly managed by the owners. There are no absolutes.

FlipKey seems to be hooked up to Trip Advisor. It also appears to have properties professionally managed.

My experience with AirBnB is the same as Kaeleku's. I love Booking.com and often use them if only to place a reservation I may later need to cancel shoudl I find something I like more. I also use HomeAway and VRBO a lot, especially for apartments. Start looking and booking as soon as you can since June is busy and larger apartments scarce. You might like this 3 bedroom place on Venezia. We did!

I love that you are spending a quality amount of time in each place, and not just a few nights. We have spent 24 nights in Venezia alone in the pat 4-5 years. A week in each in Firenze and Roma will allow a thorough exploration of the cities and perhaps a day trip or two as well.

I also have used Homeaway and VRBO many times and have had very positive experiences. The Slow Travel Italy site has independent reviews that I trust as they are not associated with the actual booking sites.
Staying at least 5 nights in one place is definitely the way to go and renting apartments will let you spread out a bit, grocery shop and pretend you live there:)
There are great day trips from Florence so you can easily find things to do for a week. In Rome, even though there are day trip possibilities, staying a week just in the city will give you time to actually see and experience the city without the mad rush from site to site.

After completing my research we landed up booking a Studio in Rome through VRBO, an apartment in Florence through AirBnB and a studio in Paris through a private rental agency. This is just how it went down after I shuffled through so many apartments, sent numerous emails and searched countless reviews (love slowtravel!). So don't limit yourself to just one website or method.

I have used Airbnb without problems. I just read the reviews thoroughly. Never tried booking.com, but many people swear by it. Also, trip advisor will give good, helpful reviews. Sometimes I just google "apartments in..." and see what pops up.

I think the amount of time you are spending in each place is great! Orvieto is a nice day trip from Rome.

I have done well in the past with Airbnb, Booking.com, IHA (for Venice), Homeaway and VRBO.

Having said that, after a very bad experience with a Booking.com property last month, I do approach them knowing this now:

1. They do not verify the properties.
2. If a property is unacceptable on arrival and you decide to not stay, you cannot leave a review; as you are no longer considered to be a client who has stayed there.
3. The only help they will give you on the spot, is to look into their system to see what's left available to rent/book - which is not really helpful in a high demand and high-priced area at 5pm, standing on a sidewalk, cellphone in hand, when you need a bed that night!
4. There is no adequate Customer Service response to deal with issues: "I'm sorry that this is happening to you" response from Rep on phone; 'canned' response from follow-up e-mail; the property is still listed on Booking, but has no recent reviews there; but, it has accumulated several negative reviews on TripAdvisor recently (including mine).

I still have future reservations with Booking.com. But I will only use them in the future for hotel stays and I don't rely on their reviews... I now double-check on TA every time! (and on Google)

I have been happy with AirBnB. A couple of times, I found an AirBnB listing's website, using Google. Twice now, I have made a reservation, for a listing that I first saw there, directly with the owners. The rate and conditions ended up being better. However, with three other reservations, I chose to book through AirBnB because of the guarantees it offers (although I have not yet put their Customer Service response to the test).

I approach Homeaway and VRBO with caution. Owners/Managers can request to get negative reviews removed. I've never put them to the test yet either, as my rentals went well.

I'm also using Google Maps more and more to find places to stay, especially when I know exactly where I want to be.

We've never had a problem with booking.com. I've also VRBO and Homeaway successfully but only in the U.S.

We have used VRBO/HomeAway many times in US for rental houses and have booked all our Italy apartments from them for next year - all with great success. Italy apartment owners have been great about emailing information and answering detailed questions. We have great confidence in the VRBO-HomeAway payment system. Owners do not get their money until guests actually arrive.

We used booking.com for apartments for our trip to Italy this year and had no problems at all. It was handy having all the booking details in the app on the phone instead of carrying paperwork. Enjoy your trip.

I regularly and for years have used hotel.com and booking.com with no problems for hotels. I lean towards hotel.com. I think they are both high in Consumer Reports, as I recall. I get reviews of the hotels from any source I can before I book. However, I've found the rooms to be exactly what was indicated.

In two trips to Europe--mostly Italy--I have come to depend on this site right here from a tweaking/logistics/first-hand reporting standpoint. There appears to be a higher percentage of truthful people on the RS forum, that are like-minded & don't blame everyone else for their own problems/stupidity. So, I've referred to this site more than any other. That being said...

...I use Rome2Rio http://www.rome2rio.com/ to initially find out if a thought-about trip is feasible logistically.

...I use Trip Advisor www.tripadvisor.com for mostly honest reviews of hotels, attractions, and restaurants.

...I use VRBO http://www.vrbo.com for apartment-dwelling. Worked famously for us in Florence. And you're dealing directly with the owner of the property.

...I use the Swiss Rail Travel site http://www.sbb.ch/home.html for the most-accurate Northern Europe train travel info/booking.

...I use Trenitalia http://www.trenitalia.com/tcom-en for info/booking Italian train travel.

...I use 'The Man in Seat 61' http://www.seat61.com/ for European train travel advice & tips. Invaluable.

Those six sites (plus this one) should give anyone a good perspective on how to plan a great self-tour. And one more thing--if I were advising someone on how to book, unless one had a specific place/hotel/B&B they had their heart set on staying, I would book from the outside in--air, then lodging, then intra-European travel, then attractions & restaurants.

This way of thinking works much better for off-season travel, of which I am a stout disciple. I can handle a little inclement weather so much better than throngs of tourists.

Enjoy!

RE: whether 4-5 days Venice and 7 each Florence & Rome are too many or too few days...

It certainly leaves room for flexibility for daytrips, excursions, whatever--but only if you wanted to. I'd almost never say 'pack more destinations in your trip'. Never been to Venice so I can't vouch for it, but you could do a week each in Florence & Rome and still not see everything, not even close. Best part about it would be you'd start to feel Florentian or Roman about the 3rd or 4th day in each place--and it's a great feeling. Your heart rate goes down & you wake up saying, geez, I could live here. You'd start out with an espresso and roll in your favorite little café, watch the morning unfold, then plan your day. Pretty sweet.

Another site, which we have used, is GALAHOTELS.COM We have used them throughout Portugal as well as in Budapest, Frankfurt & southern France. The rates for the hotels and apartments we have found through this site have been much better than though other sites previously mentioned in other replies (i.e. booking.com; airbnb) for the same accommodation and also better rates than offered at the front desk of establishments. We are planning 6 weeks in Italy in Spring 2016 and will definitely be checking out what Gala Hotels has available. They state they check out all listings and from our experience this seems to be true. And their cancellation policy is more than fair - i.e. between 2 & 7 days prior to arrival depending on the location.