A few off the top of my head that helps with stats and gym gains are Fitness center...10* gives 3% to all gym gains.
Ladies strip club- Adds 10% gain to defense and a 25% defense passive. Also the gents strip club is the same altho instead of defense it's dexterity gains. (both 10* specials)
There is also a Farm 10* that gives energy per job points which could then be used in the gym if you want. Also, a 10* special. And, a candle shop 7* also gives energy per job point altho not as much as the farm does.
Also, for further info on specials and companies you can go here
www.torn.com/wiki/Companies and get about any info you need.