We are going to Italy in October for our Honeymoon (30 year old couple, athletic, yet like museums and art, food too) and have thought about Venice, Rome, and Florence with a possible stop at the Amalfi Coast and or possibly Milan.
We are arriving, likely in Venice after reading suggestions here, on Monday and will make this trip 12-13 days. Is this enough time to see the big 3 and possibly more?
We are, of course, looking for suggestions on what to sight-see, pay for in advance, as well as hotel recommendations.
I can't wait to hear what everyone says.

First timers to Italy!

You will see lots of museums and have great food and wine in Venice, Florence and Rome. I would stick with those places considering the time you have. Fly into Venice and out of Rome. 12 Days will give you enough but not too much time in these 3 locations. I would save the AC for another trip and not venture to Milan this time. Do your research - a good guide book is very helpful.

I think it is enough time to see the big three, and if you can keep it to those, you will have time for a few really nice day trips.

Since you like art and museums and food, I think not rushing to other areas, but taking your time to really enjoy each city is a major plus.

We are returning to Venice in October (been several times) and I have a small list of museums I've yet to visit. We've been to Rome more often, and I have a long list of museums I haven't visited.

I admit to having covered Florence pretty well, but there are still a few I've missed.

I say go and dig in to each of these great places.

You may want to plan your itinerary now to get good prices on advance train tickets.

Book hotels now.

Not that much you have to pay for in advance but if you'd like a private tour of vineyards and wine tasting, or a ride to some Tuscan towns, it's very easy to book these online.

If you like contemporary art, the Venice Biennale is on in October and the reason why we go back so often.

For hotels, post your budget and tastes and you'll get lots of recommendations.

Consider the Cinque Terre if you like to hike: five beautiful old villages that look like they were built into the side of the hills; you hike between them (or take trains or sometimes boats) through olive groves and vineyards with breathtaking views down on the ocean. The area is now very touristy, but October might not be too bad, and in early October the weather may still be nice - it was when I was there in early October 2007 (glad I had shorts for the hike!).

A diversion to the Cinque Terre might be a bit of a push in the time that you have, but it was one of my very favorite places in Italy (I'm not a big fan of museums). I know a couple who went to Italy on their honeymoon, and it WAS their favorite place in Italy...

Very generally speaking, the weather in Italy north of Rome changes after the first 10 days October, and the possibility of torrential rains start to increase. For many places, that doesn't matter, but for some places -- Venice, le Cinque Terre, wine growing areas -- you might want to factor it in. South of Rome, the dry weather tends to linger longer.

So which half of October are you talking about?

We (my finace and I, wife then) are actually arriving on the 25th of October and staying into the first week of November actually, with exact plans as to when/where yet to be determined, but as stated previously, we are going to Rome, Florence, and Venice. After some talk with a couple of acquaintances, they have suggested not to go to AC due to the struggle to get there and the seedy bus rides, theft, etc.

I think we are likely to go to Venice 3 nights, Florence 3-4 nights, and Rome 4-5 nights depending on what we choose exactly. It seems Venice is a little more laid back, yet less to do, but great for catching up on jet lag.

As far as budget, we'd like to stay in nicer places,if at all possible, and have a $6,000 budget for airfare (likely half or not quite), hotels, and food. We plan to take a little extra for souvenirs and excursions. Hopefully this is reasonable!?!

I think your choice to go to those cities is great, but while I am not a fan of the Amalfi coast, i just want you to know that getting there or being there has no more or less issues of "theft" than your other destinations, so if you want to go sometime, don't let your friends' negative impressions with regard to that stop you. And do be mindful that in transport stations and crowded tourist venues in Rome, Florence and Venice, they all have their share of dedicated pickpockets, so take precautions.

In late Oct/early Nov, some areas of Venice can experience significant tidal flooding, and you should pick a hotel outside of those areas. You can find maps online indicating where the "acqua alta" most frequently occurs.

Finally, in depends on what kind of museums you enjoy, but the idea that Venice has "less to do" than your other destinations is probably the impression of people who don't enjoy visiting museums and the interiors of historic sights in Venice, and prefer just to go wandering and shopping. But I have visited Venice 3 times for its art, staying each time more than few days, and I still have things on my to-do list.