My normal development workflow doesn't use that many different Emacs packages. With a few exceptions I've mainly worked with a "stock" Emacs distribution and augmented that with a few select Emacs packages that I downloaded manually. It worked for me for a decade or so, and it made it reasonable easy to move configurations between machines - zip & copy was my friend for that, although I've since changed that to using dropbox.
As we recently switched to git at work, I started looking into Emacs git clients and came across magit. At that point I figured a pre-built package would be nice and started looking into ELPA. I use Emacs 24 pretty much wherever I have an Emacs install so having ELPA in place everywhere came in really handy.
Didn't take very long for me to switch away from the manual package "management" to get the few minor modes and other helper messages via ELPA. I don't think I'll go back to manual management.
Guess I should check if the weblogger package - which I am using to write this blog post - is also available in one of the repositories.
So if you're still using manual package management, I would recommend looking at ELPA together with the marmalade repository. The default ELPA repo didn't include several of the packages I needed, but combining ELPA and marmalade covered everything I've needed so far.