IMO the smallest (fluid) size kicks in too early, but it's not hard to customise it. You can download a customised build[1], or override the LESS[2] or SASS[3] variables and build it yourself or incorporate it into your asset pipeline.
Personally, I use the SASS build, include only the most basic parts (scaffolding, type, grid, ...), customise the hell out of the variables, and you'd never know it was bootstrap. For reference, http://www.recruiteasy.com.au is a bootstrap-based site, using standard breakpoints.
[1] http://getbootstrap.com/customize/