The thing that pissed me off was as its a muslim country it was hard to get a beer anywhere away from your hotel. Just the odd time a nice cold one after a bit of aimless exploring would have been perfect!
everyone just goes to the supermarket just outside the city gate for beer or pasha for a night out
after 3 days in the city you will desperately want to leave. the locals will have driven you mad, don't ever leave you alone trying to sell you the same old shit. you'll enjoy those 3 days though, just don't ever plan to stay any longer
if you've got longer then the atlas mountains are amazing. can you ride a motorbike? hire one and head into the mountains, it's an awesome way to spend a day
or head to the coast at essaouaria which is pretty close
even longer then head to the sahara and play on camels
other option is to fly into marrakech and out of fez to see a bit more of the country. fez is like a smaller marrakech, same stuff on sale but cheaper and less hassle from locals. don't bother with casablanca, nothing there except a giant mosque apparently (I've not been but never heard anything good from people who've been)
drink lots of mint tea, it's truly amazing stuff