You'll probably want to complete your mission and then do any looking around the pavilion you still want to do. You will walk all around the pavilion, but you might be looking at things so closely that you'll want to step back and get a broader view at some point. And many of the missions won't take you into any of the gift shops at all. Some will take you into one. If you really want to shop, you'll probably want to go back when you're done. But overall, I think that doing the missions does take away a little of the time you'd otherwise devote to touring the pavilion. In other words, you don't take the entire amount you'd normally spend looking around the pavilion plus the entire amount of time it takes you to complete the mission.