Nancy, The Knitting Teacher (who blogs at www.theknittingteacher.com), left me a note on Ravelry about what I could do to make my Log Cabin look like a Log Cabin, next time.
I can think of 3 things
1. Too loose of a sett. Sport weight yarn is better in a 10 dent heddle instead of the 7.5.
2. Yarn too close in value, there should be a higher contrast between light and dark to really make log cabin pop.
3. Your blocks may be too small for the effect to really show with the other two issues being in play. If B is brown and R is red you have BRBRBR RBRBRB BRBRBR RBRBRB perhaps adding two more for a block of 8 will help or alternating wider blocks with narrower blocks instead of blocks of 6 threads each.
Thanks, Nancy! I'll try again next time two contrasting colors surface in my stash.