Redbird Robotics transitioned to using Weebly last year and it has allowed us to produce a
nice site. Weebly hosts for free and is very simple to use, however once you learn about web design it can get annoying.
From my personal experience with WordPress, I would consider it to be much more customizable and still very easy to setup and launch. The themes and plugins for WordPress are numerous and its blogging features lend themselves well to writing a build season blog while still maintaining a nice site.
runneals, could you also PM the free webhosts for non-profits? Thanks.