So I was feeling cocky and that is usually the beginning of my problems. I had an extra Belkin "G" router and I thought it would be fun to hang it of my Airport Extreme "N" router and split up my family network putting the Airport Express, iPhone, and iPod touch on the G network and dialing the Airport extreme up to the 5k "N" setting. Everything was working out ... sort of. I got it all going but never could get the G network to find the Airport Express.
The problem arose when I started walking around with my iPhone on a G network. We have a 1500 square foot home and I figured there would not be a problem but alas I was wrong. The iPhone was dropping the G network in parts of my house. For me that was the deal breaker. I'm going to have to consult with some of my Mac guru friends but I'm thinking I'm probably going to dial the Airport Extreme back to N/G and return to things as they were. Maybe it is not as fast but very stable and my iPhone works everywhere, including the back yard.
I'm still looking at that Time Capsule though. That may allow me to mix up the network quite a bit. Hmmm.