Xmonad user here. Sessions are wonderful. I can run one just for xmonad as a job (I like to hack that config quite often ). Another just for my VPN script (which puts out I/O stats every few minutes).

And per project, I'll have a few. Say I have one where I have one shell for compilation, one for version control, and two for testing. Give each one a prefix for the project, and I've got all that separated out. E.g.: Two projects: foo and bar: foo-compile, foo-git, foo-test-a, foo-test-b, bar-compile, bar-git, etc..

Now, I have clean shell histories (and scroll buffers) for each. I can ssh into each one as I want, and reuse my terminal windows. This latter bit helps keep my already-complex-enough window setup manageable.