I'm planning to go to morocco with my friends in april for 4 days or 5 days, any suggestions?

we'll be a group of 10 friends i guess, and we still don't know whether to go to Casablanca , Tangier, Rabat or Marrakesh, please give me your suggestions. we're 24 yrs and we luv the beach but i don't know if the weather would be warm enough to go to a tangier, but mostly we love monuments because we're architects, and we love to have fun... in a legal way :D:D