I'm building my first Steelhead rod. I'm actually going to use it for surf fishing in San Diego. The blank is a 9' 2pc Lamiglas GSH 108 2L. Just curious; what handle lengths/styles are popular for this type of blank when actually used for Steelhead fishing?

It varies based on the individual. I'll throw this out - just assemble the rod and hang the type weight off the tip that you'd normally cast with it. Now grab the rod and go through the casting motion. You'll almost instinctively grab the rod at the proper location for you. Note the place where your upper hand falls and mark that for the seat location (spinning will go under the hand, casting will go just in front of the hand). Once marked, check to make sure the butt is not too long to be comfortable when fishing and retrieving, nor too short for rod holders, leverage, etc.

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"Rough estimate" that I use for "on-line shoppers" - Measurement from the base of the palm to the outside crook of the elbow for conventional; measurement from center of the palm to outside crook of the elbow for spinning. Keeps the rod out of the suds if you're wading and provides extra leverage/support if needed on a retrieve. This also provides sufficient depth (for average fishermen) if the rod is left in a sandspike.