Staying in or around Pienza?

I got married in Pienza. I absolutely love it. It's a "frozen in time" kind of place. Parking is a minor hassle; just be aware of signs. I recommend staying at Il Chiostro di Pienza. It's a former monastery. It's generally affordable, and it has a great breakfast, courtyard, pool, etc.

That said, it Pienza is very small. You can see the entire place in an afternoon, so you will want to go out driving in the country (Montalcino and Montepulciano, and DEFINITELY make it a point to get to Bagno Vignoni.)

For my money, Pienza is the perfect headquarters. Try dinner at Latte di Luna.

We had plans to stay in Pienza for the same reasons you want to. Central and seems quiet and accessible.
I tend to take all other's opinions with a grain of salt. So RS doesn't like Pienza? I am sure plenty of others do.
My thought was that the tour groups will be there mid day-when we were out seeing the countryside- but they should all be gone in the evening when we planned to enjoy Pienza, have dinner etc.
So I do still think it is probably a perfectly good place for a base.
We considered Il Choistro mentioned above but the parking there seemed a bit iffy- I think there was also a charge for parking?
We would have stayed at Hotel Rutiliano just outside the walls with onsite parking. Looked like a nice place with easy in and out for day trips.

We ended up switching to that agriturismo near Siena that shall not be named here- and will see Pienza on a day trip.

I was in this area a couple of weeks ago. We stayed at an agriturismo about 30 minutes south of Siena and took day trips. Among our trips in the region you're interested in were Montepulciano, Chiusi and Cetona. We drove by Pienza but didn't stop. I would recommend Montepulciano (Chiusi and Cetona are nice too, but much much smaller). I understand Montalcino is pretty small too (I did not visit but it was on my list). We were there in February: no tourists = no problems with parking. From my experience, I think you'll run into the same types of driving/parking "problems" almost anywhere, judging from the parking arrangements I saw. However, if you are willing/able to walk you'll find parking outside of town. You can park a short distance out of the town and walk to your hotel (good uphill exercise - good reason to pack light).

If you stay in Montepulciano, the copper smith Rick Steves talks about in his book is very entertaining. Make an effort to visit his shop. We ate at La Pentolaccia and I recommend it (as did Rick).

But, as others mentioned, don't be afraid to diverge from the Rick Steves guidebook. Although it is a great book, he can't write about everything. If you want to stay in Pienza I would say Go For It. I'm sure you'll like it, even if it is a bit touristy.

P.S. If you haven't driven in Italy - mentally prepare for ignoring stop signs, crossing the road mid-line, no turn signals and oncoming traffic. For me, driving there was stressful. Also, bring a GPS!!!! We didn't.

Pienza is also not so hilly. After walking around a few hill towns, you will appreciate it's level topography.

Forget Rick Steves. What does he know?
In my almost 3 decades living in Florence, Pienza was by far the place in Tuscany that I drove most often on a Sunday getaway. The ideal Renaissance village, as it is known.
Montalcino? Meh..If it wasn't because of the Brunello addiction I have, I would not have bothered more than once.