Unfortunately(?), ADE is as close to a "standard" target as can be hoped for. Most of the viewers have issues, so one-size-fits-all output doesn't quite universally work yet.
Personally, I've pretty much abandoned Indesign for building epubs. The one thing (ok, maybe 2) that it can do "easily-er" than other workflows are a) embed fonts via a check box, and b) allow one to work in Word first.
But: you'd still have to have all your styles declared in Word first. And, you'd have to re-impose word quickstyles on a per-file basis (which, when you change your mind about something, is so close to starting over that you just might as well). Indesign typography tricks don't transfer, and opening the epub in other softwares tends to break the epub (because of the font encryption), and re-hacking the output file afterwards almost always breaks something in ways that I don't enjoy.
I'm finding a more satisfactory workflow to be like:
Word->Dreamweaver->Calibre->Epub/Mobi/Lit/Whatever.
I know, I know, it looks like more steps (as opposed to Word->Indesign->epub? yes, it is). And for sure, it doesn't give you the one-stop-shop approach of Indesign. If you're having to re-hack the file after indesign, you're already working harder than you need to.
css tidy, is useful for fixing up css, if you need it. But even that won't help you change post-indesign css very well.
-bjc