The first style of fitness that I gravitated quickly toward when I became a personal trainer at Equinox was Circuit training.  This is not only important for heart health, blood circulation, and increased energy levels, but it's also really FUN! 

There are many tools used such as: Cable machines, Kettlebells, ViPR, TRX, Rowing Ergometers, Versaclimber, and Sled Prowlers.  These help achieve compound movements, while increasing heart rate levels.