Maybe you're trying to get emacs to work like an IDE, which it isn't. I often have multiple projects open in emacs and just never close emacs, not for weeks. This is one of the main reasons I ended up on emacs years ago. On my current project I switch between java, ruby and Lisp. I also need features to edit jsp, erb, html and css, the only thing I haven't sorted out yet is javascript. As well as the ability to completely customize my environment, this is the power of emacs.
I do use ECB all the time, and typically as I move around files, it follows me, I don't work from a 'windows' perspective, but from an 'Im here' perspective. A particular buffer being open or not is actually unimportant. I also use IDO, so switching buffers is really easy and intuitive. I generally have two buffers displayed max (but potentially lots open). M-X s is also useful to ensure you've saved as it will enumerate all the unsaved buffers and prompt you about them.
When I do have to close emacs, I generally get back to where I was very quickly by cd'ing to that folder and type emacs app/controllers/my_controller.rb. From there the rails navigation is very helpful. M-Shift-down arrow and we're off ...