The roads are fine. The Portuguese drivers are nuts--they speed, pass dangerously and tailgate. Roads are not all that crowded, especially, I imagine, in the fall when the tourist season subsides. Road signs are more difficult than Spain but far easier than France (and by the way, I speak/read French but not Portuguese). Definitely go all the way to Cabo Sao Vincente, it's one of the most beautiful places on earth. If you do, I recommend Rick Steve's favorite in Salema, the A Mare
http://www.algarve.co.uk/Page1.htm We stayed in Apt A, and put our kids next door in Room 6. Of course, you may not get it in the fall because Rick Steves fully books it for his tours. But try anyway--it's fantastic, and run by a Brit expat. The beach there is wonderful, and definitely drive over to the Atlantic coast from there. If you're not a surfer you'll wish you were.