There is wine that comes from the Loire valley - I've had it - so it would logically follow that there would be wineries, though I've never toured any myself. I think what makes that region shine is the history and natural beauty. As for where to stay, the various chateaux are scattered along the river, so I honestly don't know what the best option is - when I went, it was a group trip, many years ago, organized by someone else, and we made several stops. I imagine you'd want to choose a 'home base' town from which to explore the various castles, or pick a couple cities that are the most interesting and from which you could do day trips to see anything/everything else. I believe you can also do a cruise down the Loire, though I've never looked into that myself.
As for which cities, I do love Nantes - it's got great culture, and an ancient (i.e. medieval) castle (being the former capital of Brittany) and is just very quaint and lovely. Other major or historically significant towns that come to mind are Tours, Orleans, Blois, and Angers, from which you could easily get to castles such as Azay-Le-Rideau, Chambord, Chenonceau, and the tiny city/castle of Amboise - and, presumably, wineries. These will be much smaller towns than Paris, of course - you won't get the big city feel, but rather a small or mid-sized French town. Very walkable, usually, but with good public transit if you need it.
(Also, do keep in mind that my degree is in French literature and history, so I'm a bit biased towards all the historical stuff; still, I think you won't be disappointed even if you're not a history buff. The countryside is beautiful and the food remains excellent even outside of Paris).