Admin themes --- which, again, cost tens of dollars --- are uncannily similar to Twitter Bootstrap: they include full page layouts with dummy navs and a series of demo pages with styled markup for... well, more than is in Twitter Bootstrap! (They get to cheat and use jQuery). They are basically what you'd get if you gave a designer the brief "build the layout for my app, Lorem Ipsum 3.2 Pro".
You really ought to take a look at them. I know it's hard to take things from Themeforest too seriously. It was hard for me too. Now I feel dumb about that.