For mine, I shot for ~40mph. If you haven't seen it already, BrianG has a really cool speed calculator available:
http://scriptasylum.com/rc_speed/index.html (click "Top Speed Estimator")
Throw in the various numbers, and it will give an estimated speed at WOT.
SH Z-Car, Custom Crawler, 8s Savage,
12s XTM XLB 1/7 buggy,
4wd 4-link rear/IFS Pro4 truck,
Custom Hyper 10 Short Course,
Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz