I guess I always pictured the Brewer house being more of an artless McMansion, which I know isn't accurate since the house is old.
But wasn't Abby's house a new construction? (And so likely to be a McMansion?) I don't know if it's realistic that they would be building new mansions right next to older historical ones.
I thought mrs. Stevenson bought an old house and completely redid it. But it is feasible that, say, someone had an estate and sold it to a developer and they built McMansions there. That's happened on the street where I grew up a few times.
"You may not believe this, but I was good at acting evil."--Karen Brewer
Several times in the early BSC books it was pointed out that Mrs. Porter's house was an old victorian and it had gables and turrets. I don't think the Thomas/Brewer mansion had those, because it would probably be mentioned.
We know Watson's mansion had a circular driveway. (It's mentioned in book #8, which is the one I am reading right now.)
Now I'm not exactly sure if it was mentioned that Watson's mansion was a victorian, but I found a few pictures:
That's what I found by searching "connecticut mansions"