Traveling within Morocco has proven to be easier than I thought it was going to be. The main train line goes so many places and is pretty inexpensive. I've used the train line countless times, not always without fail, but it has gotten me to where I needed to be.
ONCF Train. You can find the website here and its a one-stop-shop for everything you need to know about the trains.
I've traveled the following routes:
Mohammedia to Fes (1st class: 165 MAD; 2nd class: 109 MAD one way). This trip was beautiful and passed by pretty quickly. We traveled through the mountains and saw olive groves and grape vineyards...it was just beautiful! The train station is kind of outside of downtown so walk out of the train station and walk for a little bit and you'll likely get a better rate on a taxi to where you need to go.
Mohammedia to Marrakech (1st class: 154 MAD; 2nd class: 105 MAD one way). This trip is a long-haul for sure! I would definitely recommend a first class ticket or catching an early morning train. In second class, they sell more tickets than seats, so a seat is not guaranteed and the cars get pretty hot and stuffy pretty quickly. I bought a 2nd class ticket for the noon train out of Marrakech and it was like nothing I've experienced before. There were women throwing children and large luggage bags up onto the train so that they could all get a seat.
Mohammedia to Tangier (1st class: 186 MAD; 2nd class: 124 MAD one way). This is also a long-haul trip and always takes longer than advertised. It's a beautiful ride, but I would definitely recommend a 1st class ticket. I was even able to lay down across 3 seats after the sun went down. The train station in Tangier is currently under construction, but it is right in town and close to everything!
Mohammedia to Casa Port (2nd class: 16 MAD one way). This trip is really easy and takes about 30 minutes tops. Sometimes we wait longer on the platform for the train to come than we do on the actual train to Casa. There is a McDonalds and Starbucks in the Casa Port train station so we always look forward to that pit stop when headed into Casa.
Mohammedia to Mohammed V Airport (2nd class: 59 MAD one way). This is also an easy ride from Mohammedia with a transfer at Casa Port. The one-way journey takes about 2.5 hours.
Taxi. Taxis are so convenient in that they are everywhere and you can almost find one anytime you need one. They are color-coded for each town so they'll be easy to find. They are lime green in Mohammedia, royal blue in Rabat, and red in Casablanca.
The minimum fare in Mohammedia during the day is 7 MAD and at night it is 10 MAD.
Public Transport. I’ve never ventured onto the public transport buses here in Mohammedia, but I’ve seen them very crowded and heard they run horribly off schedule and aren’t very reliable. If you are running short on time, this doesn't seem to be worth the money savings.
Plane. Some of the cheapest flights I've found, domestic or international, have been out of smaller airports like Rabat, Fes, or Marrakesh. I've also found that its been more economical to book "multi-destination" trips and I've been able to see more for about the same price. If time allows, the cost savings would be worth the couple-hour train ride to the departure city. I found Kiwi a couple of years ago and it has been my favorite flight search engine since then and the prices are the cheapest I've found 90% of the time.