The cooler months have some great gobular cluster sights particulary in the Sagit/scorpius region but the warmer months have a plethora of wonderful Open Clusters to check out.
Theres the Pleiades and Hyades of course but direct your attention and scope to canis major and youll find a number of Messier catalog examples like M41,M50,M93,M46,M47,M48. Near Saturn youll find the Beehive M44,M67 and nearby in the constellation Auriga M38,M36,M37,M35.