If you choose a text font with rounded corners you'll end up with something probably too frivolous, as well as pudgy rendering at smaller sizes.

Here's an idea: invert the motif and choose a font with rounded insides, which is most commonly exhibited in the transition from stems to serifs. So choose a font with fully adnate serifs, that come out of the stems in quarter-circles. And if it's a slab that would emphasize the effect. This leads me to recommend my favorite slab, Egyptian 505:
http://new.myfonts.com/fonts/linotype/egyptian-505/

BTW, in that pointy circle in the logo the transition from curves to lines seems to be suffering from the classic "bone artefact".

hhp