> I am considering doing a fairly large project with Ruby and 
> XML, and I'd
> like a summary of the benifits and downsides of the various available
> modules from someone with experience.  My project will 
> generate perfect XML
> and then read it in subsequently, so I don't need to worry 
> about validation.
> Ease of use is a big priority, and speed is not terribly important.

I'd also recommend REXML, and I'll throw a new project of mine in the ring:
Xml Serialization. It's still in the pre-release stages.

http://clabs.org/clxmlserial.htm