Plan your route
The Via Michelin web-site is a fabulous source of information. Not only can you choose the route to include/avoid motorways or toll roads, you will also be provided with the total distance of the journey together with the estimated time it should take. It also provides information on toll costs which is great for budgeting.
While your Peugeot will come with an inbuilt GPS, good planning will help you avoid spending more time than necessary driving. If you are traveliing with children, they are sure to thank you for it!
Tourist Board web-site addresses:
Czech Republic: http://www.czechtourism.com
Slovak Republic: http://www.slovakia.org/tourism
And for a list of UNESCO World Heritage sites: http://whc.unesco.org/pg.cfm?cid=31