I use both a tiling window manager (xmonad) and tmux. The main reason I started using tmux was to do pair programming sharing the same terminal via ssh. If you pair program and have never tried this before, I highly recommend trying it. I live in Japan and even pair with people in London using tmux and vim. It's the next best thing to being there.
After I started getting used to using tmux, I found that my workflow naturally separated between things I'm doing on my terminal and things that require X (like my browser). These days I use a separate workspace for X apps and terminal (occasionally moving them around).
To make my life easy, I've added xmonad-like key bindings and window layout to tmux. Since other people are sharing:
https://github.com/ygt-mikekchar/dotfiles/blob/taka/home/.tm...
I often work while travelling and when I'm on the road I often don't bother cranking up X -- just work in the Linux console. Using tmux I barely notice a difference in my workflow and it helps extend the battery.