Exactly what I'm thinking. I am pretty sure I'm not a celebrity.
I am actually thinking of using separate domains now. I realized that subdomains might be useful for separate blogs on related topics in the same niche, but for completely diverse topics, multiple domains might be the preferred way to go, especially since there is always the chance of some of those sites developing into something more than a blog, even if that plan doesn't exist right now. I tend to think in terms of possible future expansion.