That could be fun in C-130 for example! But C-130 cool by itself too :)

But i really think that for commercial airliners, -  take FSPX and it'll give you ton of challenges :) Especially for 727 and 707. How about to arrive within 15 minutes of preset time. How about to do that in VATSIM  :o

Thats hard. I cant do it still.

Another idea - is to create missions in style of tutorials. That could help to master new aircraft.