I use a laptop and I make heavy use of workspaces. I generally don't use an external monitor at all. However, when working at a desk, I use an external keyboard and trackpad, and put the laptop on a stand.

I dislike plugging into a monitor because it I hate the chaos of resizing everything. When I'm on the large monitor I unconsciously expand things; then when I switch back everything is on top of everything else or expanded beyond the window edges or reflowed or what have you.

I say this having worked with applications where you truly need an external monitor: image editing (where you put all your extra palettes on the extra monitor, and DAWs, where timeline and mixer views take up a full monitor each. Programming isn't like that.