I'll second most of Nick's statements.

I use "Yellow carpenters glue" almost exclusively now (with some epoxy for firewalls and wing joints etc.). I only use CA when I'm feeling lazy or making a hasty repair. I'm a bit concerned with the long term effects of CA and the number of people who've developed nasty allergies and side effects from inhaling it.

The carpenters glue is easy to work with, light, flexible and stronger than wood. It fills gaps well, cleans up with a damp rag, sands well and, when combined with sawdust, makes a decent filler.