In just over two hours the TGV train from Paris whisks you to Rennes, the region's hub. From Rennes you can continue to the region's farthest outpoints—Brest and Quimper—or take a branch line to St-Malo or Dinan.
You need to use buses, or a car, to explore the coast between Dinard and Rostoff, and the smaller towns along the Atlantic coast, like Concarneau, and Pont-Aven. The A11 expressway leads from Paris to Rennes, continuing as the N12 dual-carriageway to Brest, whence the N165 dual-carriageway heads down the coast toward Nantes. Roads through the Breton hinterland are narrow and slow.