I'm running Ivan's Eris Official 1.0 at 710MHz max. and 245MHz min. for my main settings. For my profiles, I've only enabled "Sleep/Standby" (set to 480 Max, 245 Min) and "Failsafe Profile" (set to 43 degrees C, 245 Max, 245 Min).
Note: Ivan's 1.0 ROM is kernel-locked to 710MHz, so I can't go any higher without flashing Zanfur's kernel patch and a newer version of setCPU. But, I'm happy with this speed since its safe and does the job for me.
Others have posted some of their settings here:
http://androidforums.com/all-things-root-eris/98457-overclocking-hmm.html