People who have the quality of congeniality have a gift for getting along with others. They are warm, friendly, and probably well-suited to serve on welcoming committees.
The noun congeniality is closely related to the word geniality, which means "friendliness." Congeniality can be defined the same way, but the Latin prefix con, or "with," adds a sense of connection to other people. If you can't get elected as Prom Queen, strive for the title "Miss Congeniality."