I'd love to do a tour de Chandler too, but I'd definitely be in a whole different class of speed than it sounds like most of you ride. I have a slow hybrid bike with 700x45 tires and I'm more like a 14-15mph rider than 15-20mph. There's only so much you can do on a 65-70psi tire.
Still, I've been getting up at 4am every other day for the last month and riding about 25-30 miles so if I can really get my fitness level up then I might just barely be able to hang with the back of a 15mph group. The longest ride I've done so far is 50 miles, but I'm working on pushing that too.
I guess that's the tough part about cycling versus the motorcycle guys for example - motorbikes can be anywhere from 25hp dirt bikes to 175hp crotch rockets and still hang together on a ride at legal speeds, but with cycles the difference in equipment and humanpower can mean the difference between a 4 hour or a 7 hour ride. Still, if somebody wants to draw up plans you can count me interested too. I too can only do Saturdays, but since I'm so much slower than most guys who are more fit and have faster bikes, it may be irrelevant anyway.