Hey Doug,
I had a great time in Key Largo last year, but the Spiegle wasn't upright yet (it was still spectacular). The Bibb, Duane, and Eagle are all good wreck dives. Also, the Thunderbolt is definitely worth the drive down to Marathon. The French reef is very nice if you like reefs.
I can't recommend my dive op, because they committed the mortal sin of "dive time limiting." (ie. on a nice 30fsw reef dive, they said we had to be back on the boat in 60 min, and we could have easily stayed for 90 min) But I've heard great things about Silent World. You might be able to find some good information in this subforum for the Florida Conch Divers:
http://www.scubaboard.com/forumdisplay.php?f=55
Have fun on your trip,
Mike