PSG, Dortmund and Brügge, please. Shortest possible travel distances. Roughly 2.300 miles in air distance to-and-from all three cities combined.
The second closest combination of teams we could possibly face (excluding all of the above three) would be Juventus, Porto and Hoffenheim @ ~4.450 total air miles, almost twice the travel distance.
Longst possible would be Moscow, Shaktar and Galatasaray @ ~10.300 air miles.