Going to mostly limit this to the Olympics.
Expand the Summer Olympics to three weeks to allow for more athletes / sports / events without balloning costs.
Specifically, have a rotation of which athletes are there. I like the idea of having one week tentpolled by swimming, one week tentpolled by Gymnastics and one week tentpolled by Athletics.
Eliminate Modern Pentathlon from the Olympics
Expand the athlete quota for the Winter Olympics to around 3,500, reverse athlete quota cuts and add some new non-traditional sports (especially ice climbing, cross country running, cyclocross and snow volleyball) to add appeal for more non-traditional winter sports countries.
Obviously, lets also expand the program for the Winter Olympics to include things like freeride, rail jam and a team moguls event :D
And the big one:
Create a "mind and skill sport" Olympic games, name still a work in progress. Would be a home for stuff like e-sports, chess, go, bowling, cue sports, perhaps even motorsports.