In the old, pre-Ruby & Rails days o' the web, one typically used PHP when they needed to add server-side functionality that HTML or CSS could not provide. Nowadays, we have a ton of options for creating super-dynamic websites and applications. I recently discovered that you can just use .erb files on a web server to get the same functionality as throwing PHP files in there in order to make things more dynamic.
I am building my first from-the-ground-up website, which will actually be my own personal website. I'm a huge Ruby nerd, and definitely want to invest in the technologies I'm most learned and familiar with. I want to build with a focus on simplicity, speed, and power in mind. I love Rails, and have had the most training in it, so I am, for the time being (for version 1.0 of my beloved sexy website), excluding Sinatra or other frameworks from my list of choices.
Now, here's the question, which is admittedly a bit ambiguous: when is it appropriate to go from using regular old .erb files to using a full-blown Rails framework? The website won't be processing any users or anything, and will mostly be a portfolio for my art, music, and technology works. I'll be doing a blog with Jekyll, additionally, so that level of dynamic content will be handled separately.