Decide upon
Definition 1 of 1
Pro Tip 1/3Thoughtful Choice
Use 'decide upon' to show a choice made after careful thinking, not a quick or random decision. 
She decided upon studying law after considering all her career options.
Pro Tip 2/3Final Decision
'Decide upon' implies that a final choice has been made and there will be no further changes. 
The committee decided upon the winner after extensive discussions.
Pro Tip 3/3Common Pairings
Commonly used with nouns like 'plan', 'date', 'location'. Indicates a choice in a specific aspect. 
They finally decided upon a venue for the wedding.