I actually haven't used it myself. I do my own strength at home with dumb bells and a ball using mostly SP moves. I try to stay out of the gym as much as possible and prefer to be outside but I do still end up there about 2-3 times a week, sometimes more- for cardio. The machines are set up in an order but you can start where you want. There are step-up platforms in between each machine that you use in between exercises. Maybe your trainer can set up a circuit for you that is quick, or maybe 3 circuits (do each circuit one time per week) that are different but work the same muscle groups so you don't get bored on the same machines. You could jump rope or hop on the treadmill in between for the added cardio element.
I belong to Planet Fitness- it's really cheap ($9 a month) and has the basics... it's a national gym so I'm including the link to their page that discusses the 30 Minute Circuit. www.planetfitness.com/pepf.aspx?clubid=103
Hope this helps!