Alright, I went out an bought an Airport Express and after a few tries got it integrated into my network. I considered setting up a separate network with it but quickly realized that would be a total PIA having to switch back and forth between networks. In any case I have it working quite seamlessly with my network and am able to stream from my computer, iPhone and iPads. Pretty cool. There are only a couple issues that I think I'll just have to live with for now.
First, I am transitioning to iRule as the remote for all my home systems. If I am streaming music via Airplay and switch to iRule on the same device, the Airplay stream is paused once I start iRule. Not a big deal as I can just use a separate iDevice or remote and keep the stream flowing. Think I may post on the iRule board to see if there is a workaround to this, though I think it is a limitation of the iPhone/Pad.
Second, I have the Airport Express set up on my existing home network. As previously discussed I will have to provide the password to any guests who may want to stream music. Once again, not a big deal as there aren't many people who come by that I would hesitate to provide the password to. Hopefully once Airplay Direct comes out this issue (as well as the previous issue) will be resolved. The good news is that it looks like I only have to be connected at some point on my network and not necessarily in range of the Airport Express to stream music. This is compared to if I had set it up as a separate network where I would need to be in range of the AE.
Ultimately I would like to be able to set up an open guest access point for music streaming and internet access. However, I would also like to be able to integrate the router into our network with the proper password so I could stream content from any device while concurrently allowing for another connection such as to iRule. Until that becomes possible I am quite happy with what I have now though.