Hi, settle in for a long read.
EJ, maybe you won't be lonesome with your new 12. it is shaped like a...oh never mind...
I'd like to share my take on 12 strings. I don't understand why there aren't more of them used these days when the general quality of factory 12's is pretty good.
I always disliked alot of 12's just because they didn't sound "warm" enough for me, and my first one's top couldn't even be felt to be moving when strummed hard, unlike my 6 at the time that rang and vibrated like crazy. When I had a 12 made (Marc Beneteau, St.Thomas Ontario), I took alot of chances design wise, but happily they were worth the risk.
Because I screw around with tunings, I wanted a stable neck, so I ordered a 12 fret (to the body) neck which had the convenient benefit of also moving the bridge back into the wider area of the top, which I think improves the tone, volume and clarity. This also meant there'd be no problems with standard tuning, which is an issue since its often used in a band context where I don't always have the time or liberty to mess with tunings. For my personal use however I can up the gauges a bit and detune somewhat. DADGAD sounds like the earth opening up to swallow me.
The body size of many 12's is more designed for a 6 string so I opted for a tighter waisted shape, almost a 3/4 jumbo sort of thing. This reduced the boom, particularly in front of a microphone. Marc adapted the top bracing and the top is lively but controlled. I wish I could thank this guy enough for how he's acommodated me, and his incredible work.
To reduce the weight of the headstock thereby improving the balance on my lap I have ebony tuner buttons which are significantly lighter than steel ones, and look great. Perhaps mock pearl (plastic?) would look good too. I figure that 12 tuners are heavy enough. (I once saw a 12 string player with different buttons on the octave strings to help the player tell them apart, but I thought it also looked lousy.) The balance is also improved by the 12 fret neck, and guess what, it fits in my good hardshell 6 string case.
I didn't want a cutaway since I obviously like playing low anyway. But my other concern was with the soundhole being moved back the distance of (roughly) 2 frets, the top area ahead of the hole would be increased and I thought I'd like to exploit that a bit, no matter how it was braced. I have no way of knowing for sure how this worked except to say I don't miss the cutaway, and it sounds glorious, loud and full.
Wood wise I chose rosewood back and sides, spruce top, mahogany neck and ebony for everything else. I don't think woods are a fussy part of 12 string consideration, except that I've never heard a plywood top 12 that I liked, and I think ply tops require too much bracing for the 12 string tension.
Having burdened you generous readers with all this detail, I have still been impressed with some factory 12's lately. The Yamaha, Martin (even the less expensive ones), are quite acceptable. I never thought I'd say this but I heard an Ovation 12 tuned low last year (I think at the Owen Sound Celtic Festival) which was surprisingly clear. Perhaps it was the combination of 12 strings and low pitches which improved the plastic sound. With the current interest in citterns and octave mandolins and bouzoukis (why doesn't that word look right?) and the like, a 12 string can sometimes even pinch hit for those sounds if retuned, that is if you can suspend your disbelief awhile.
I just scanned this post and I obviously like talking about guitar concepts, anyone share this interest?