We always enjoy staying at apartments while in Italy. It usually gives us more room to roam around in.
You may or may not find them to be cheaper than the inexpensive hotels for just one hotel room. We usually need two rooms when my dad travels with us and can find some savings with apartments.
We have generally used agencies not VRBO.com.
things to look out for that you won't have seen if used to hotels.
There is almost always a final cleaning fee, most sites give you the cost upfront.
there may also be fees for utilities like heating or AC or phone on top of the rental fee. Although these days most places wrap those into the rental fee.
You'll also need a security deposit to cover damages at most rentals.
there are a few spots that only rent weekly and then only a Saturday to Saturday stay. A lot of places will now go with a two or three night minimum.
Make sure you know where the rental is located. Use google maps to verify.
www.slowtrav.com has a number of apartment reviews for researching rentals
IF you find what you think is a perfect spot and it only has one week minimums, you might want e-mail them your dates anyway. Sometimes they will be looking to fill in shorter gaps between their longer rentals and you'll luck out.
Most rentals will require a deposit up front. Sometimes it can be significant, like half the fee. Some places want the whole thing beforehand. Make sure you are aware of the cancelation policy. Some won't refund at all if you cancel and they can't re-rent your slot.
Having said all that, we like rentals a lot more than hotel stays.