This is the first time I have ever seen anyone suggest cedar is acceptable in 15 years.
Generally speaking cedars are strongly believed to reduce immunity and irritate the lungs leading to health issues. Any natural wood that have insecticide properties should be avoided. Use insecticides of any sort only when needed not everyday. At the end of the day they kill things and are not really very discriminate.
Hides any thing can work, personally I look for a handful of things. Non porus, no open holes everywhere. A U shaped opening. I never use anything with a closed O. They snake should never be able to become stuck inside a hard closed circle. (after a meal they are bigger and less flexible)
Fit the enclosure properly. If you have little floor space ones that fit into the corner is better than round ones. If there is lots of floor space it doesn't matter.
Not have sharp bits. Sometimes a hide has a sharp place from casting or forming but can be lightly sanded to smooth it off.
(posted sites are just for the pictures, not a place I suggest buying from!!)
(exoterra ones) http://img.diytrade.com/cdimg/166678...hide_rock1.jpg
I like these for the look. They need a stiff brush to clean them however.
http://www.mrherp.ca/shop/reptile-pr...arge-hide-box/
Very practical utilitarian hides.