How about qualifying rounds for the tournaments? Now even if I am ranked #150 i still get in the main field of every tournament just by a click. It would be nice an more realistic, if you had to qualify for a tournament when you are not ranked high enough. So you would have to choose wisely if you try to get in to a "500" tournament where your wuld have to qualify or if you take the "sure" "250" tournament where you get easily into the field but will get less championship points.
Another thing I would suggest are courts that are not a stadium for each tournament or et least each kind of surface. It is not very likely that is will play my first round game as #150 against the #12 seed at center court in wimbledon. More likely I would play on "Court No. 12" or so. The mentioned qualifiers could also be played on this courts.
Last thing: Will it be possible at any time to create new tournaments or even new seasons? So one could create his own "challenger series" or anything like that?