I'm curious what everyone has clipped onto, zip-tied to, or in their BC.
I carry a back-up (or primary) light my right shoulder / chest strap (clipped to a D-ring, with the head bungeed down to the strap), a lift bag in a sleeve, clipped to the bottom left (vertical) side of the plate, and a SMB bungeed along the bottom horizontal edge of that plate, and my primary cutting tool (EMT shears) on my right waist strap. Everything else (spools, wet notes, compass, back-up cutting device) is in pockets (on my exposure suit) or a pocket on my waist strap.
I . . . am going by way of a traditional octo. What do you recommend to keep it handy and in control? Thanks and looking forward to everyone's answers!
Good question. Although i happen to personally favor the use of a 'long hose', I more generally recommend the following configuration to new(er) divers, and teach its use in all of my private OW classes:
1. Put your alternate air source (nee 'octo') on the shorter of your two second stage hoses (usually 32-36"). Put a bungee necklace on that second stage, and position the second stage under your chin when diving. That way, your alternate is always right where it should be, and where you can easily access it, to put it in your mouth in the event that your primary regulator gets knocked out of your mouth, or you need to donate it to another diver, in an OOA situation (unlikely, but possible). IOW, in that position it is definitely both 'handy and in control'.
2. Put your primary second stage on the longer of your two second stage hoses (usually 40"; often it is a yellow hose). Route the hose under your arm, and possibly add a 70 or 90 degree elbow (an $8 item:
Swivels and Elbows | Dive Gear Express®) between the end of the hose and the second stage to facilitate routing. That second stage becomes the one you donate in an OOA situation - you know it is working at the moment you donate it, it is on the longer of the two hoses, and it is the one that an OOA diver is most likely to immediately see.
I see no point is wasting time with, and money on, the various 'octo holders' that too often leave your alternate air source dragging behind you. Even the pockets that are now appearing on some BCDs (e.g. Aqualung) are less than optimal. In an OOA situation, if you are diving in proper horizontal trim, the
one second stage that an OOA diver is likely to see when they approach you is the
one that is in your mouth, not one that is somewhere lower in the (Bermuda) 'triangle'. That is the one you should donate. Then go to your alternate which is immediately accessible, under your chin. And, you can set up this configuration without changing hoses - the common hose lengths work just fine.
. Try to pare it down for what's needed for the particular dive, but like air, you need what you need. 
