Changes the park has undergone throughout it's history? It was designed to be Marriott's Disneyland, a chance for the company to convey it's hospitality and show in the theme park industry. It was extremely well themed and known for its cleanliness and service and each area had it's own costumes to convey the theme, the resturaunts and food were themed to the specific area. Some of the inspirations from Disneyland are still highly visible from the firehouse to Orleans Place.

Marriott decided not to be in the theme park biz anymore and sold to Six Flags in 1984 [Six Flags was owned by Bally at the time]. They continued to add rides regularly [most noticeably ZForce] and started the ride rotation program. Weresay bought the Six Flags company in 1987 and continued to add rides [most noticably Shockwave]. Theming slowly started to dissapear in favor of more generic branded stuff in the park.
Time Warner bought the Six Flags company in 1992 and did all sorts of good for the park adding popular and well themed attractions like BTR and Southwest Teritorry incl Giant Drop and Viper as well as the stunt show. Time Warner sold Six Flags sometime around 1999 to Premier and thats when the park (and all Six Flags parks) started going on a major downhill slide. The quality and clientele at SFGAm became much more teen-oriented and mostly all the themed costumes were cut. They added Bull (which was already planned by Time Warner), V2, DejaVu, SUF, and pretty much neglected everything else in the Six Flags Parks. They also managed to take the company in a tremendous amount of debt that still saddles them today.
In 2004 the company turned the page and started focusing on the quality and family appeal of their product more with Mardi Gras, then the next year followed suit with additions like Hurricane Harbor at Great America and the Golden Kingdom at Great Adventure. Unfortunately for them it was too little too late and they still had too much debt. The next year SF's board of directors allowed Dan Snyder's to buy a major stake in the company and name the new CEO (who is Mark Shapiro).