I spent ages fiddling with my vimrc to get whitespace displayed just the way I wanted. It was awkward because some of the UTF-8 symbols I wanted to use didn't reproduce properly on all of the terminals and systems that I use. A time saving alternative might have been Better Whitespace (GitHub: ntpeters / vim-better-whitespace) by Nate Peterson, a plugin for highlighting trailing whitespace.
Whitespace for the current line will not be highlighted while in insert mode. It is possible to disable current line highlighting while in other modes as well (see options below). A helper function :StripWhitespace is also provided to make whitespace cleaning painless.
Once it's installed you can toggle whitespace with
:ToggleWhitespace, or even just toggle the current line with
This fits in with my policy of doing as the Romans do, and you could easily add your own mappings by following Daniel's examples.