What I'm really looking for is something more detailed/feature-rich
than the RTB. Something that would allow inserting images, multiple
font sizes/boxes, etc. Almost like a small version of Word in a text
box (without having to use or install Word).
I can recommend TX TextControl (
http://www.textcontrol.com/), it's not
cheap but will do what you want - we used it in two projects so far,
and it has worked perfectly as a Word replacement. It can even be used
as a report generator, to some extent.
Phil