Divide and conquer.
If you leave the shoulders whole, you will be cooking for about 1.25 hours per pound at 250
That's 20 hours(!) for the 16 pound shoulder.
You should also consider injecting for a more flavorful product.
Definitely wrap at 160F - it makes the end product much more juicy. And cook it until it reaches at least 188F internal - 195F internal is better.
Divided the 8 pound pieces will take about ten hours. The six pounders about 8 hours.
Be sure to have a temp probe in them as they cook. Some pork seems to hit a plateau at around 165 to 170F for a long, long time. Other pork seems to only stay at the plateau for a short while. So it's important to keep a close eye on the internal temps.
I personally like your idea of the combination of apple with a little bit of hickory for your seasoning wood.
I like to eat pork in slices. Especially on a sandwich. Be sure to get really good rolls if you can. Most bakeries that make their own stuff will have some decent rolls or buns for sandwiches.
I like my coleslaw on the side - and not on the sandwich - but that's strictly personal preference.
Thanks for sharing this with us!