There is a wonderful application for OS X called
Disco. It makes burning much simpler than the built-in Finder options, with the added touch of a smoking CD burning window which makes burning fun. I have found one problem with it though, the Spandex system doesn't always correctly span your files across multiple discs.
Everything appears fine when preparing the burn:
And Spandex seems to parse things correctly, saying multiple discs are required:
The first sign something is wrong is apparent when the second disc starts burning. This is a 1.38GB span over two discs, shouldn't disc two be much fuller than this:
When looking at the discs after the burn
(disc 1)(disc 2), only the Reception directory was burned, the
rest of the files were left off the disc.