Italy with 4 year old

You will have no problem with crowds at beaches in October, they will be deserted.

Why a beach in October? There's a reason they'll be deserted.

It doesn't have to be near a beach, but we thought it might be nice. I'd love to hear about any little towns that are an easy train commute that are near Milan or Venice. Thanks!
Alisha

Also, can anyone recommend a fantastic travel agent?

Not sure about your staying in an agriturismo if you are not renting a car. I've found taking trains in Italy to be fun and relaxing. Venice might be nice. You can take the vaporetto to the Lido. Not sure if it will be beach weather. But might be nice for your little one to explore. You might want to think about renting an apartment. We use vrbo and have had success with them. We've rented in Venice through them twice. Having your own apartment will give you the flexibility of not having to eat all of your meals in restaurants. Also, if your little one gets tired, it's easy to go back to an apartment and take a nap and rejuvenate.
How long to you intend to stay in Italy? More advice would be forthcoming if we knew how long you have. Also would recommend that you read Rick's ETBD and his Italy guide. Lots of valuable info. We don't use a travel agent for traveling to Europe, so can't help you on that front. Actually find the planning part of the fun.

What were you hoping a travel agent would do? If you let us know that, then people can give specific recommendations. These days, travel agents are less useful for most people than in the past. They have to charge a commission for most things, so most people do basic booking on the Internet themselves. Only some have specialized knowledge that is really worth paying for. I've also read that if you intend on staying in truly luxury properties, travel agents can still get discounts on these. For what you've described so far, with Rick Steves Italy (and other guidebooks), websites, and e-mail, you can do the research and booking yourself.

Our plan was to stay for a week - 2 days in Milan is all that's certain. Everything else is up in the air. We won't have a car so I'd been advised to take the train from Milan to Padua, make Padua our home base, and then take the train into Venice. I know nothing about Padua (other than it's cheaper than Venice), so any advice on that front would be appreciated. As far as a travel agent, I thought that they might be useful in pointing us to where we should base ourselves for the week. I agree that an agriturismo probably won't work, but I'd love to find a charming, walkable town that we could explore. (We'll probably be flying out of Milan so we don't want to go too far away, but I'd love to see Florence, too.) Thank you, everybody! Grateful for the guidance.

Is that week an actual 7 days in Italy? Or is that a day of traveling on each end which makes it 5 days in Italy? If it is 5 days I would do the 2 days in Milan and 3 days in Venice. Otherwise you are doing a lot of traveling on trains back and forth, which in the end may not be cheaper.

I spent 3 days in Padova, after spending 3 days in Venice, and loved them both, for different reasons. Padova is much less touristed than Venice (or most other "famous" Italian cities), and has the amazing Giotto frescoes. It's also a nice place to hang out in, and as a smaller place than Venice, can be more manageable. But Venice is unique; your 4 year old won't appreciate what makes it so special, but you will. It is also expensive, and hard to find good food in. Different strokes. I think either one would make a nice stay with a child; you certainly could take a day trip by train from one to the other. As for a travel agent being able to advise you on where to stay -nope. Once upon a time (when our Earth was young, it seems), travel agents made a commission for every flight booking and almost every hotel booking. So, they could afford to consult with customers "for free" about where to go; some of them might have known what they were talking about, but many didn't. But now, there are no commissions. So, if you want travel advice, you can either ask here and on other travel forums, and read guidebooks, for free. Or you can pay an agent - by the hour - for a consultation; there may even be some who are worth their fees. But, I'll bet you'll get just as good advice here.

Bergamo, Padova, and Verona are just a few of the possibilities that I would suggest. You don't really want a small village as you'll quickly run out of things to do.

Its certainly not easy to find to comb through all the different places to stay in Venice and not think everything is as high as the moon. But there are gems in that there muck. Pension Guerrato. We paid €135 (no 4 year old though) in April. We have no need to stay elsewhere now. Yes maybe Padova is nice to walk around, and we do really love the Giotto frescos at the Scrovenghi Chapel. But Venice is Venice. We stayed on the mainland several times and trained in but truly the magic starts after all the daytrippers leave.

Lots of good suggestions. I'd add Como or Varenna on Lake Como. If your four year old is like ours were, boating from town to towns would be just his cup of tea. Como is an easy train ride from Milan and you can explore the lake towns by boat once you're there.