Dunno if you're still considering this as it's an old topic, but I thought I'd offer my two cents. I've got one on my shoulder blade, sounds like about right where you were thinking. It did hurt. A lot. It only took about twenty minutes (about 3 1/2 inch lightning bolt). The initial pain isn't bad, but as it goes on, abrading the already swollen skin is unpleasant. Still, I hear the longer it goes on the more endorphins kick in and it can be better. I love my tattoo. I'm planning to get another one and being really bold about it. Putting it on my wrist. I have the luxury of not having to work if I don't want to, so professionalism isn't a concern for me, of course having them where you indicated wouldn't be visible in the professional world anyway.
I waited a good year before I got my tattoo, and am so glad that I have it now. It's a very good idea, of course, to check out the shop as far as cleanliness is concerned, but it's also really important that you like the artists style. If you know anyone in your area that's gotten work that you like ask where they got it. In my area most of the artists focus on that 'american' style which I'm not too crazy about. I like something more artistic with simple lines and a more original style. It took awhile to find someone that did this, but it was well worth it.
Hope you're happy with whatever choice you make.