You would not absolutely need to rent a car at either location. You can take the TGV from CDG to either Tours or Dijon. Either destination takes about 2 hours if you select one of the direct trains. For the Loire Valley, I would stay in Tours. purchasing a train ticket for Tours Centre, not St Pierre des Corps. Tours Centre is in the center of town, about a mile from St Pierre des Corps. For a stay in Burgundy either Dijon or Beaune are excellent choices.
I would check train schedules using the
SNCF´s website; but the actually timetables are not typically official until 90 days before any given travel date. They sometimes post earlier but not generally 6-7 months earlier unless you are looking at raileurope, a place from which you should rarely purchase tickets.
I don´t know what you expect to find
vineyard hopping, but don´t expect easy access to any of the Burgundy vineyards. Strongly consider hiring a professional guide who will make your time much more productive than if you attempt solo visits. You can find a list at the
Dijon Office de Tourisme. If you plan on staying in Beaune, I would look at the
Beaune Office Tourisme.
The vineyards of the Loire Valley are often family affairs and are not particularly setup for visits, particularly in English. Again I would consult with a private guide or take a tour from the
Tours Office de Tourisme. An advantage of the Loire Valley is the area´s rich history and abundance of outstanding ch teaux which add to the area´s interest.
If you do go to the Loire Valley and stay in Tours, I might suggest that you stay in or around the area of Vieux Tours or old Tours. This area has restaurants, cafés and some nightlife. Other areas of Tours are not interesting for tourists.
Staying in Tours, you might consider
la Maison Jules, a very comfortable chambre d´hôte located in the center of Tours.