Something to do, please. To quote Ideocracy, "I like money", but come on man wheres the drug dealing. TP Industries has a decent meth lab, how about I keep inventory of what was made, sold, stolen, and destroyed and based on that information call up Merryweather to assist me in taking out my rivals.
The stock market would be interesting if there were any way to clearly manipulate it outside of Franklins Assassination Missions like stealing goods to resell back on the black market or destroying shipments.
Franklin was frequently mentioning "Forum Gangsters" which Lamar quickly shot down, the option to go forward on that idea now that Franklin is in a great position would include selling weight for Trevor (mostly cocaine or other drugs that TP Industries doesn't deal with), selling stolen vehicles (online only right now which is strange), dealing on the stock market (cleaning the money), stronghold management, and recruiting.
OPEN BAHAMAS MAMAS, I cannot stress that enough, there's so much to be had in that establishment.
Michaels career in Hollywood should expand, opening a deeper dynamic with his family, specifically his daughter, and creating dynamic situations for the family. With that comes connections to key people who can influence public image which can influence the economy. This then opens up more heist opportunities. The more Michael contributes to this end the better the scores, unfortunately this will have to be balanced with his personal life.
VIGILANTE MISSIONS, nuff said.
I believe everyone has covered everything else but I know for certain with these enhancements the replay ability won't be such an issue, as it is now.