Yeah, if you do some heavy renders (lots of texturing, lots of geometry) with Mantra or Karma, you'll see an application that is well multithreaded and probably get to test your memory performance with more accuracy than with simulation. Mantra/Karma are "trivially multithreaded", meaning every camera ray can be thought of as a little program and uniformly executed in a separate thread in a rinse&repeat pattern. There are shared memory caches and such but those have been well tuned for multithreaded access. Simulation has gnarlier phases that often require traversing the simulation data in different ways, and some of those methods are harder/less effectively multithreaded, but still might be interesting to use as benchmarks due to that very reason.
To test memory properly, however, use a dedicated benchmarking program that tests different memory access patterns. How those benchmarks apply to real-world programs is rather dependent on the program in question, of course.