I am positive someone has thought/suggested these but I searched and couldn't find anything. So here it is.
1. Option to upgrade aircraft/hubs for WiFi connectivity
, and set price/make free to customers. Also could have this in place for the gate/airport area at hub.
This seems to be pretty simple to add, as it would only affect CI making people more likely to fly your airline and could cost a fixed amount per connectivity level(airport) and number of aircraft(WiFi inflight). However it could have a large impact with customers when multiple airlines fly a route at default prices and the same/100 CI...
2. Option to actually paint your aircraft with livery
. Would greatly influence CI, as well as deter airlines from simply ditching a place before C check and re-leasing another for 2.5yrs of whatever the length may be.
Again with this investment in the aircraft, airlines would be less likely to turn-over aircraft, especially leased aircraft so quickly.
Annnnnnnnd GO with the critiques!