I try to run my Systema classes in the same way as at Vlad's school. We try and keep every session fresh and interesting and are usually working on a range of things - though sometimes we may spend a few sessions on say, just knife work.
A typical class will involve a range of exercises, from simple warm ups through to strengthening / stretching. Correct breathing is emphasised throughout, with specific breathing patterns worked .
The bulk of the class will be partner work - one or more partners. Drills range from evading through to working form contact. This may be done against grabs, punches, kicks, or against weapons, knife, stick, occasionally we do some basic gun work. We also do pad work.
As I mentioned we may work against just one partner or sometimes against a group. I also like to throw in some work from seated positions, on the ground, blindfold, etc.
I may show some "techniques" to give the guys some ideas, but we try and free-style it as much as possible. Sticking to the principles is the key thing, then people learn to adapt to the situation as they need to.
The exercises are interspersed throughout the class and, depending on what sort of mood I'm in ;-) may range from fairly light through to intensive.
We finish each class with everyone sitting in a circle passing comments or asking questions about the lesson, that way we get some interesting feedback.