Casablanca just after your visit to the mosque and the Cornish skip it to Rabat where you can have an overnight there in some riad near the Medina, there is beautiful ones around.
- From Rabat i'd suggest Chefchaouen, for 2 nights.
-Fes 2 nights, one of your arrival from Chefchaouen and other one after you explore Fes using a city guide ask your riad for hiring one for you, or just manage yourself.
- From there try to go to the desert Erg Chebbi most beautiful desert, then skip it after a desert overnight, experiencing camel ride.
- go from Merzouga to Boumalen or Ouarzazat. then to Zagora if you like but in my opinion if you visit The erg chebbi there still nothing worth in Zagora.
so from Ouarzazate, go to Taroudant.
Taroudannt to Agadir2 night in it. then to Essaouira for 2 to 3 nights.
Marrakech 3 to 4 Nights, as you can make some day trip to the high atlas mountains, Ouzoud Falls or Ourika Valley.
You can drive easily hire a car at the air-port once you arrive there in Casablanca, and drive using the Map, and don't go without a guide book.
have a nice vacation.

Sorry i did not see that you are arriving in Fes, so departing from there after you stay 2 nights in Fes, then visit Meknes, Volubilis, overnight in Chefchaouen the blue town.
2 Nights in Chefchaouen.
1 Night in Rabat.
skip Casablanca after a short passing visit to the Mosque, head direct for Marrakech 5 Hours from Casablanca to Marrakech highway driving.
one night there and go to Essaouira.1 night
1 Night in Agadir- 1 Night in Tarouddant- 1 Night in Ouarzazat- 1 Night in Zagora back and overnight in Ait ben-haddou.
Back to Marrakech and stay the rest of your trip relaxing and exploring the sites.
have fun.

visitmorocco.com good legit info for you.
Use only reputable agents
MANY agents touts scammers here/there check profiles carefully
ALWAYS pay with Credit Card never wire money.
When there last for the high Atlas Ulta Marathon
I trained seat61.com/morocco and booked my hotels on the fly.
booking.com agoda.com good reputable for booking hotels
oattravel.com has GREAT tours itineraries might have a look there.

PM if needed Happy Travels!

Welcome to fodors. Unfortunately, the Morocco section of this board is peculiarly susceptible to spammers. You can safely ignore all of the answers so far.

Instead, go spend some time with some guidebooks. You know your own interests better than we do (hiking, camel riding, camping in the desert, eating, shopping, etc etc) and a guidebook (e.g. Lonely Planet) can tell you what you'll find in each place. Your library may have some, otherwise camp out at Barnes and Noble with a cup of coffee.

You might also try reading trip reports here (click on my name for mine).

Could not agree with you enough thursdaysd.

Thank you Interpid for your advice, we'll watch out from you.

It has been a few years since we drove around Morocco, but I hope you speak either Arabic or French. If not, try to learn some before going. It will really help. Morocco is a challenging county to get around in by yourself once you get out of Marrakech, Essaouria, etc. Chefchaouen is definitely worth visiting. We loved it. We made our night arrangements one day ahead of time as we traveled around. Actually in Marrakech, we just parked our car and didn't use it again until time to drive on to the next place.

Nowadays; Morocco become more developped and mostly speaking English so no worries about languages, driving also is easy if you are not right side driving i mean like ( Aussie.British...driving), so Morocco has good roads, as you'd better take the highways, you'll arrive Fes rent a car in Fes and drop it in Marrakech.
From Fes Air-port to Marrakech Air-port before departure, so when you have specific question after you plan exactly the places, you can come back with specifiic question regarding your trip, as you know there is places worth to stay in more than 1 night like Fes, and Marrakech at the head and Chefchaouen, Essaouira as well. other places 1 night is enough.
For Money exchanges, you could use debit credit card in Morocco with no problems at any ATM's but keep in mind BMCE recommended for tourists, read the Guidebook to get more information about such hidden things, for more specific information.
The Weather: No one can give correct updates about what it will be tomorrow, it keeps changeable all the time, but last years due to the experiences it's Hot which means better to take light clothes and some warm as well, and keep in mind that you have no problem about how to dress up, You can dress like whatever you like but try not to leave eyes attraction to get some harrassments from guys in some places, moreover; give some respect to the local culture. So long sleeves is good.
Water: Sidi Ali, Ciel those are the most used and known quality in drinking Water, so to avoide stomach diseases better to drink the meniral water, and use the Tap water with no problem.
During June; Morocco has some events which you can live and enjoy your trip during:
-In Fes: 08-16 June 2012 there will be the world's festival of the Sacred Music, held in Fes.
-In Essaouira: 21-24 June 2012;Essaouira Gnawa and World Music Festival.
So; i'd suggest to base your trip to live the both events as you'll see more local events as Morocco always has new and special things to Offer.
If you have anymore questions about your trip planning this is your forum to share and regular members will help.

"and mostly speaking English so no worries about languages" - not my experience. Buying a train ticket at Casa airport, for starters, I needed French. My feeling was that having learned one European language, people didn't see a need for another.

That's happened to you because in Casablanca, people speaking French more than any other language. But above i spoke about places no need to more French because people also have problems with it but young people there speaking English and Today Morocco has increased at the educational field.
People got well educated at least people, youth can speak them both, you'll find a little diversity North of Morocco, Tangier and surrounds speaking spanish more than others.
All in all; take a guidebook, and learn some french words to use which are often in use there.