In terms of the way the races are laid out over a year I don't really like the current model. Maybe one or two races change a year at maximum but that's it. Would much rather see a static 10 to 12 races and add 8 to 10 (totalling 20) from the other circuits and maybe rotate through them biennially. Say, for example, you had these races annually (until a contract is up anyway):
Melbourne, Montreal, Monza, Silverstone, Suzuka, Austin, Monaco, Spa, Shanghai, Abu Dhabi, and Brazil (between Sao Paulo and Rio);
and then having races split between certain circuits such as:
Malaysia and Singapore; Spain and Portugal; Austria and France; Germany and the Netherlands; Azerbaijan, Bahrain and Russia (two of the three each year); Hungary and Turkey; Mexico and Argentina;
And a gap for a race like the Vietnamese GP or one into Africa or the return of India or Korea or something.
Meh, think I'd like it anyway!