If we keep the same basic format, i.e. 4 Slams, 9 Masters and the Tour Finals, what events would you like to see? In terms of location, surface, court speed, etc.
Australian Open - medium-slow HC
Roland Garros - slow clay (slower than it has been in the past few years)
Wimbledon - fast grass (a lot quicker than it's become over the past decade)
US Open - medium-fast HC
Tour Finals - fast HC
As for the Masters, I'd switch some around. Ideally make Dubai a 1000 event and Halle/Stuttgart as a grass masters (before Wimbledon) which I think is sadly missing from the calendar. Not sure which I'd get rid of though to make it all fit in the season