Went to Marrakech in May 2016. Lovely place, great people and great weather.
Stayed at some Aqua Fun Park because it was cheaper - it was outside the main city, about 20-30 min taxi journey away but it was all-inclusive. Huge complex with about 4 different pools, 3 massive separate apartment blocks and about 5 or 6 restaurants. Not to mention the actual water-park itself which had so much to offer. 5-night stay at the princely sum of £55/night. Flights were only about £100 return as well as we went just before half-term so got decent prices. Literally the only downside was that it was Ryanair we had to fly on .
One thing you have to do when going Morocco is visit a/some of the Riads. They're like hotels but have an open courtyard area to dine/drink in or just chill out in. Highly recommend seeing them as you get to see real culture of the city/country. I'm sure there'll be loads in Agadir as well.
Plenty of market stalls/bazaars no doubt as well.