I use Ruby on Rails professionally and personally, and it addresses most of your features very easily (with Devise being a popular auth system that can be added).
Ruby follows duck-typing, so variables are not typed. If that was a strong point for you, Ruby might not be what you need.
I'm not quite sure about the admin UI (I usually use the rails console when I have things to change), though, but there's probably a gem that does exactly that (?).
Ruby on Rails is very powerful and intuitive, and I'll miss it if/when I change jobs and have to use some other language.
Edit:
> [...] so variables are not typed.
I might have used the wrong words... Ruby is dynamic, strongly typed. Variables are not limited to a certain type after they are created, and can change anytime.
Ruby follows duck-typing, so variables are not typed. If that was a strong point for you, Ruby might not be what you need.
I'm not quite sure about the admin UI (I usually use the rails console when I have things to change), though, but there's probably a gem that does exactly that (?).
Ruby on Rails is very powerful and intuitive, and I'll miss it if/when I change jobs and have to use some other language.
Edit:
> [...] so variables are not typed.
I might have used the wrong words... Ruby is dynamic, strongly typed. Variables are not limited to a certain type after they are created, and can change anytime.