Some very interesting observations on the information submitted so far.
1. There is no perfect length rod for everybody...it is subjective.
2. Try as many different lengths as possible before you buy.
3. Your needs and requirements will change as your experience levels grow in the sport.
4. Small changes in length can produce significant changes down field for a given user.
5. Length is important but, when combined with the rods action it gives the particular rod its effective overall length so to speak. (a 12' rod in one action may be perfect but effectively too long or short in another action)
OK, we can see length is one of the most important aspects in selecting a rod but it has to be combined with the action and the physical characteristics of the caster. How do we help those entering the sport to decrease the learning curve and select a UK manufactured rod sight unseen (usually) that they can effectively compete with?
If you have ever bought a Zziplex you know exactly what I mean on the term "a purchace in faith". Zziplex posts little information on the specs of their rods. Length is about all we can get information on. The reason for this exercise is to help those that feel "well, I will just go ahead and but brand X's top of the line tournament rod and grow into it". This might never happen. Infact, that rod maybe the worse choice for your specific needs and you will very quickly grow disenchanted with the sport and give it up because the rods length or action may not ever fit your style or physical dimensions.
I am sure there are lots of good surfcasters, or inland bait fisherman who think they would like to enter this game of distance casting. They may dial up sites that show very expensive specialized equipment and there goes the desire because of cost or lack of the knowledge on what they should purchase starting out. We owe these casters the benifit of our experience if we want this sport to grow.
We may need a "formula", as LongRanger suggested, so that we can plug a persons size, strength, weight, and level of casting and suggest actions and lengths that won't handicap the user. Any ideas?????