Hi bunny4jeff,
We drove to Turkey and back as we wanted to bring our dogs into England without putting them in quarantine. {A Link to an old CBF topic was here - no longer available}35961 We also visited a lot of places to make it a holiday as well. Quite a few people on the forum have travelled over and taken different routes. We travelled with Sat Nav and maps and made for Clerment Ferrand where there is a volcanic area to visit which is interesting.There are hotel chains in France and they have good web sites.We stayed there for a look around. The crossing into Italy at the Frejus Tunnel in Modane cost 35euros and took about 12 minutes.Rivoli near Turin (Torino) was our next stopping place for a rest.We made found the Davide Hotel there which was convenient for a quick rest and then we visited Pisa, Florence and Rome for a few days staying in hotels. I would not advise driving in Rome but stay outside near a train station.There is a bus travelling in a circular route in Rome which you hop on and off with one ticket.
We then caught the ferry from Brindisi,just turned up and bought a ticket.Brindisi was a very pleasant area and we went for a meal whilst waiting for the overnight ferry to Igoumenitsa. We then drove across Greece to Kavala for a night in one of the hotels and a lovely meal on the sea front.There are no service areas on the Egnatia motorway that I saw.We had driven to Thessalonika but did not like it there much so did not stop for long. We crossed into Turkey at Ipsala quite early in the morning and were asked for our Green Card and papers but not searched. Some cars are searched.We then made for one of the ferries across the Dardanelles 25TL.If you want to visit the wartime landing sites make for the second ferry crossing and it is in that area. The ferry itself does not take long to cross the Dardanelles and you catch it at Gelibolu or Lapseki (Lord Byron swam it). It was a very pleasant short journey,just time for a cup of tea!The road to Izmir is coastal and passes Troy(Truva) .The big wooden horse near a cafe gives it away.We also stopped at Akcoy where there was a small mall with toilets and La Tazze Coffee etc.Once at Izmir head for Bournova and pick up the toll road to Aydin 2.5TL,then make for Mugla and then Fethiye.
On the return journey we crossed to Ancona in Italy (Superfast Ferry)and a very helpful steward called Georgiou) and stayed in the Asti area overnight at the Cascina Bella Vista.Once in France we lived there for seven months and visited loads of places!
I am sure others on the forum can suggest different routes for you.
As to the expense. I would use a RAC or AA route planner to work out the cost of petrol by expected mileage. The cost will depend on if you stay in hotels,visit places,eat out etc. On the ferries you may or may not book a cabin.People were sleeping on deck with sleeping bags and pillows. I wish you luck with your plans!

I am sure there are cons but can't think of any at the moment!
