I would only make two changes to the Yas Marina Circuit, both at the end of the long straights. Currently, at the end of each long straight is a tricky little section that discourages a driver from trying a pass as it puts them out of position for the next bend.
After a long start/finish straight, too many of Tilke’s circuit end up in a tight hairpin then loopback (Sepang, Nurburgring, China), I decided to open it up a bit and create a few sweeping corners leading into a hairpin (passing opportunity) which then leads into another hairpin deeper into the infield (more passing). From there I would return to the middle sector that is has a range of sweeping and tighter bends.
At the second last corner, I would open up the corner and keep it going further left and head out to a tight final turn to encourage a last lap dive.
I’ve made the track a bit longer but should generate a couple of more passing opportunities on an otherwise boring circuit.