Hello Julie and thanks for asking the Disney Parks Moms Panel such a fun question!
Epcot is one of my families most loved Disney Parks, there really is something for everyone be they young or simply young at heart!
I'm absolutely sure your very own secret agent son will enjoy going undercover and trying to solve
Disney's Phineas and Ferb: Agent P's World Showcase Adventure! You are quite right in assuming that selected World Showcase Pavilions host their own missions which on average take from 30-45 minutes to complete; currently these Pavilions include - Mexico, Norway, China, Germany, Japan, France and my very favourite the United Kingdom!
Remember that before embarking on a mission Guests need to collect a F.O.N.E or Field Operative Notification Equipment by visiting one of the recruitment centres found at Epcot's Odyssey Bridge, Norway, Italy or near International Gateway.
If I can sprinkle any extra pixie dust onto your upcoming Walt Disney World Resort vacation please pop back to ask me another question.
Have a great Disney day.
~ Jane