Simple:
* Our family had a reunion at the lake this summer.
* The reunion was filled with laughter and memories.
More complex:
* The high school reunion brought back a flood of bittersweet memories.
* After years of being apart, the reunion gave them a chance to reconnect.
* The reunion was a bittersweet celebration of the past and a hopeful look towards the future.
Figurative:
* The band's reunion tour was a triumph, proving that their music still resonated with fans.
* After years of separation, the reunion of the lost dog with its owner was a joyous occasion.
You can choose the sentence that best suits the context you're writing in.