Caryn A. Tate wrote:

Thanks so much for all of the tips. My balloons and their tails are looking much better now!

A bit late, but... I also run a webcomic (with weekly issues) where such balloons are used heavily: http://nicubunu.blogspot.com/search/label/webcomic

I do them as rounded rectangles and I always do an union with the tails made with beziers (sometimes the tails are straight, sometimes thei are rounded).

What I tried was to place the text inside balloons as *flowed text*, which was a number of advantages (mainly it allowed easy translations with .po files but also is good when moving the balloons) but I dropped it as I also make available the SVG on the web and Firefox is not able to display flowed text.