When it comes to expressing positivity and happiness, there are various synonyms for the phrase "in good/high spirits" that can be used. One such synonym is "feeling elated" which refers to a state of extreme happiness. Another term that can be used is "buoyant" which implies a feeling of lightness and cheerfulness. "Upbeat" is another synonym that suggests a feeling of optimism and positivity. Someone who is "jovial" is also considered to be in good spirits and is known for their cheerful and friendly demeanor. Lastly, "radiant" is another term that can be used to describe someone who is glowing with positivity and joy.