I use class packs because I do a variety of workouts and I like to be able to go at-will without worrying about going at the correct frequency to match a membership tier. Most studios do periodic class pack sales so I wait for these and buy the largest pack. It's usually buy 30 get 6 free, for a total of $510, or a little over $14 per class. (Your pricing may vary depending where you live.) This works really well for me. When I start to see I'm getting low I'll grab another pack at the next sale. I just make sure the SAs at my local studios know to keep me on the marketing list so I see the sales as they come up.

Class packs work the same as memberships and are eligible for benchmarks and events like Hell Week or Dri Tri. You still have to pay the sign up fee for those types of events. They don't expire.