/usr/local is the default location for user-installed stuff, but I personally like to have my package manager do its stuff in a separate directory. I like the way Fink [1] uses the /sw (software) directory. Does anyone have a valuable opinion on the comparison between Fink and Homebrew — or maybe MacPorts? [1] http://www.finkproject.org
Homebrew is, by far, the most pleasant package manager I have ever used.
I couldn't even tell you why, but it's just nicely designed, and shit just tends to work. Part of it is that it targets a very well-defined system (MacOS), and it has an explicit aim to integrate with that system as well as possible. (I guess this could be true of e.g. apt on ubuntu, but ha ha ha.)
As an example, most package managers have some funky, one-off , more-or-less shitty way to update the packages list. Homebrew has...git! Which works great.
I highly recommend checking it out.
Another example: Most package managers say, "you're installing random software off the internet? Better give it root access!" Homebrew installs as the current user, no root access. Much saner default policy, IMO.
Or maybe you want to see a list of installed packages? "brew list". Oh, you wanted one-per-line, that's "brew list -1", just like ls.
Or maybe you want to install some software from a 3rd party repo? "brew tap $somewhere; brew install $something".
It's just a very thoughtful, well-made piece of software. Strongly recommend checking it out.