I found the following summary of the design tradeoffs imposed by inductor core type useful. I hope this helps someone else try to figure out whether they want a ferrite core or a toroid core.
“Renco: ferrite stick core inductors; benefits are typically lowest
cost and can withstand ripple and transient peak currents
above the rated value. These inductors have an external
magnetic field, which may generate EMI.
Pulse Engineering: powdered iron toroid core inductors;
these also can withstand higher than rated currents and, being
toroid inductors, will have low EMI.
Coilcraft: ferrite drum core inductors; these are the smallest
physical size inductors and are available only as surface
mount components. These inductors also generate EMI but
less than stick inductors.”
Source: http://www.national.com/ds/LM/LM2678.pdf (see Inductor Section)