Hi Steve. First of all, it's not a "fear of heights". It's a rational and strong sense of self-preservation. Who in their right mind would willingly and recreationally put themselves in a position where a fall would end their life? duh. Climbers are insane.
That said, falls on major routes with proper precautions in good conditions don't happen very often. It's as safe as driving.
I'm very afraid of heights. I won't go into details, but i had one real freak out moment, and since then, every climb with any exposure has been uncomfortable. I would suggest you reconsider SW Couloir. Under proper conditions and with very well-reserarched and meticulous routefinding, it's not that bad. Helmet for sure. Keeping your group very tight so that any loose rock can't travel far before hitting someone. But it sounds to me like that's the way to go for you. The exposure is minimal and there is no rappelling. Rockfall danger can be minimized, and after being up there, wuss that i am, i think that falling danger isn't that high as long as you're on route. I didn't take notes or have gps info, but i'd be happy to tell you what i can.
And if you don't go, no big deal. It's all a silly made-up construct anyway. Now that i've done Gannett and Granite, what i think about most with them is that i'd like to go just hang out at Titcomb Basin again. It doesn't even matter if make the summit.