Thanks for getting back to me.
Bootstrap has quite a lot of styling going on for forms (after resets, there's 300+ short lines of css for various form elements, and another 350+ lines for buttons), so I won't paste all that in here.
However, here are are some relevant excerpts from the documentation, to give you an idea of what it all does:
"Individual form controls automatically receive some global styling. All textual
<select> elements with
.form-control are set to
width: 100%; by default. Wrap labels and controls in
.form-group for optimum spacing."
.form-inline to your
<form> for left-aligned and inline-block controls."
"Use Bootstrap's predefined grid classes to align labels and groups of form controls in a horizontal layout by adding
.form-horizontal to the form."
"Use the .checkbox-inline or .radio-inline classes on a series of checkboxes or radios for controls that appear on the same line."
"Bootstrap includes validation styles for error, warning, and success states on form controls. To use, add
.has-success to the parent element."
"Set heights using classes like .input-lg, and set widths using grid column classes like
I realize that accomodating all of this (even just some of it) is a lot to ask, and I understand the need to balance flexibility/extensibility with ease of use, so if the filters aren't there, I won't ask you to rethink the entire contact form plugin.
I'll shop around a little bit. But thanks again.
(To anyone else who comes here looking for something similar, Contact Form 7 and this post might be a good place to start looking.)