We have had teams in the TARC National Fly-offs for 2006, 2007, and 2008.  We have looked at the weights of the rockets, the altitude achieved, and the motors used.  Here is a table that works for Aerotech motors to about 800 feet.

Weight (grams)	24mm	29mm
300 to 400	E18 reusable E28 reusable E30 single use
400 to 500	F24 reusable F39 reusable
500 to 650		F20 single use Econojet F42 single use Econojet F40 reusable
650 to 850		F25 single use F50 single use F52 reusable
850 and above		G64 reusable