Thanks for the sage advice! My artist is the one who suggested one sitting. According to him, after subtracting prep and break time my actual under the needle time should be roughly 5.5-6.5 hours.
My primary motivation for getting it done in one sitting is my desire to use holidays for healing time. My next window would be late May and I really don't want a half done job for that long!
Great advice on the choice of foods, and I especially appreciate the tip on ibuprofin as it's my go-to pain killer.
My wife is driving me to and from as we live way out in the country about 45-60 minutes depending on winter roads. My artist told me flat out there was no way he'd let me out the door if I had to make the drive myself.
I got a 14 hour 1/2 sleeve on my upper arm in 3 sessions, a month between each. The timing was my artist's choice, not mine and I'm glad. 4 hours at at time was enough for me. Not entirely the pain involved, sitting/laying for long periods, being tensed, etc. I just find it to be more enjoyable to do shorter sittings, I have nothing to prove. Also, some tattooers have a heavier hand than others.
Couple things that I'd add to Dan's list. No ibuprofen, aspirin or other blood thinners before (of course unless it's something very necessary and then I'd run it by you doc and/or let your artist know.) If you're traveling very far right after, I'd suggest stopping for a quick meal. Even with a snack during the tattoo I felt much better refueling before the drive home.
Best of luck and let us see how it turns out.