I felt like if I installed Python 3 I'd still need Python 2 around. Didn't have a solid setup for supporting both and still being able to use virtualenvwrapper et al. I think I can just wrap some aliases like mkvirtualenv2.7 and mkvirtualenv3.3. Any better ideas are welcome.

The decision seems reasonable to me. One could use virtualenv (included in the VM) to spin up a virtual python 3 environment when necessary.