How do I use the riscv-tests suite?

I have (eventually) worked out how to build the riscv-test suite, but how do I use it?

I can obviously run the different benchmarks like this:

spike dhrystone.riscv

But how do I access the different test virtual machines? All the different pieces seem to be built under the isa directory - but how do I use them in such a way I get meaningful output?