Both of those gave me a lot of difficulty, but a tip I found out on the Bugatti:
Drift that long curve before the straight. It was way quicker powersliding through it than trying to baby it through the corner. Ended up a couple seconds ahead of gold on that one. Know which corners you can late brake on, and which ones need you to slow down sooner.
The Aventador, all I can say is focus on hitting the apex and coming out of the bends as fast as possible.