marc rosen writes:

To those who have built beds, what have you used and are you happy
with the results? Anyone tried more than one type of fastener and
found one better than the other?

I would suspect those rail fasteners are wobbly.

My son's old bed rail broke, and I had to replace it. The hardware was
old and odd looking. Incredibly, the Woodcraft store had the exact
replacement!

It's a Sheraton bolt.

http://www.woodcraft.com/family.aspx?FamilyID=1096

It's very strong, and easily tightened - after the bed is together.

Lee Valley has bed bolts
http://www.leevalley.com/hardware/pa...=3,40842,41269

These are similar to the Sheraton bolt. Perhaps easier to install.

The Sheraton requires you to mortise in the square bolt, while the Lee
Valley just requires a hole.