By car you can reach Tours, coming from Paris, within 2 hours (237 km), using the highway Nr. 10 (A 10).
Nantes is about 3 1/2 hours (384 km) via highway 11 (A11).
The express train TGV from Paris Gare Montparnasse takes to Tours 1 hour and 10 minutes and to Nantes 2 hours.
If you want to go there by plane you can fly both to Tours and Nantes.