Hickorybutt's given you good advice, a pork butt gives you a pretty wide margin for error. Just make sure you have contingency plans in place for variances in the timing. Word to the wise, it''s a lot easier to deal with food that's done early than it is to deal with hungry guests when the food's not done on time. Butts can take anywhere from 8-25 hours. Seriously. So as a new smoker, my advice would be to smoke your butt a day or 2 ahead and reheat the day of the party. It really won't suffer in quality and you'll have a lot more fun not freaking out about whether it's gonna be done.
As for your Dad's request for surf and turf, there are a couple ways to go there. Tradition dictates fillet and lobster, which is incredible on the smoker. I'd reverse sear the fillet and hot smoke a lobster tail. You may be setting a dangerous precedent though :)
Another way you could go is to do the pulled pork (turf) and make smoked lobster rolls (surf). I'd just hot smoke some lobster tails and then do a traditional lobster roll. The mayo will mask a good bit of the smoke flavor, but it'll still be there as a subtle backnote. Being in MA, you no doubt have access to New England style split top rolls, and if you butter the sides and toast on a hot grill they'd be mighty delicious for the lobster rolls.
Also, don't forget appetizers. ABT's, moink balls and pork shots are all crowd pleasers. A search here on SMF will get you tons of recipes for each.
Lastly, don't forget dessert. A simple fruit cobbler is always a crowd favorite, and the easiest way I've found is just making a "dump cake" with canned peaches. I don't have a recipe handy, but another search will get you several. Another favorite around here is a clone of a popular Caribbean rum cake. It's probably my favorite dessert. Here's the recipe I use, which I've put together from several other recipes. I just copied this from an email I sent to friend, so it's a little tongue in cheek in the wording, but the recipe is all there. It uses a Bundt pan.
Preheat oven to 325˚
1 box yellow cake mix. I used something like ultra moist golden butter recipe or something. It doesn't really matter. Disregard the directions on the box
1 3.4 oz box of jello instant vanilla puddin' (the smaller, normal sized box, not the big one)
4 (yes, 4) eggs
1/2 cup oil
1/2 cup milk
1/2 cup rum
Dump everything in the bowl of your super duper red stand mixer with the paddle attachment on it and mix on low until incorporated. then scrape down the sides of the bowl, and (now this is important) crank it to high until the batter lightens in color and thickens noticeably. It won't be super thick, but it's easy to recognize when it sort of changes. Usually 3-4 minutes on high. Don't use the whisk, or it'll whip too much air into it and you'll have something resembling styrofoam. I made one that I just sort of mixed together and stuck in the oven and it wasn't as good.
Oil and flour a bundt pan. Make sure you get all the nooks and crannies.
Dump a half cup of walnuts evenly around the bottom of the pan. The recipe calls for finely chopped, but I just sort of whacked the bag a few times with a rolling pin, resulting in fairly large pieces. This way the cake batter cooks into the nuts giving it that praline like quality.
Dump the batter in the pan. Now, not to sound anally retentive here, but be careful not to slop it on the sides or the middle thing on the pan. This cake is a pain to get out of the pan anyway, and crusty splatters of batter make it all the more difficult.
Once you have all the batter in the pan, give it a little twist and smack it on the counter a couple times to let the air bubbles come out. Then, take a flat rubber spatula and smooth out the top. This will be the bottom of the cake and no one will see it, but if you don't do this, it can sort of rise weirdly and unevenly leading to a lopsided cake. If you smooth it out, it'll all be even.
Bake in the middle of the oven for 55-60 minutes. Check at 45 just to make sure.
Let it cool for about 10 minutes.
While it's cooling, make the soaking glaze:
Melt a stick of butter in a medium pan
Add 1/4 cup of water
1 cup of sugar
Bring it to a boil and stir constantly for 5 minutes. BE CAREFUL, this is REALLY hot and it likes to foam and try to boil over. Keep stirring it and it should be fine. It will get thicker and the bubbles will kind of stack up on top of each other.
Remove it from the heat and add 1/2 cup of rum and a teaspoon of vanilla. It may bubble up for a second when you put the rum in, but it won't explode or anything. Probably.
OK, we're almost there.
Now try and remove the cake from the pan. I've found that if I take a butter knife and run around the outside and the middle, it makes it easier. Basically you're just making sure the damn thing won't fuse to the pan when you add the soaking glaze, forcing you to eat it with a spoon standing over the kitchen sink. Don't ask how I know.
Anyway, pop it out of the pan, then right back in.
Then take a chopstick or something roughly the same size and poke holes all the way through the cake about every inch or so. Seriously, you want A LOT of holes.
Then pour the soaking glaze on. Usually I'll pour half directly on the bottom of the cake, then the other half around the rim of the pan where the cake has pulled away from the pan. Yes, I know it sounds fussy, but if you just dump it all on the bottom, it'l be soggy on the bottom and dry on the top.
Now let it cool completely, about a half hour or 45 minutes more.
While it's finishing cooling, you can make the other glaze.
Sift 2 cups of powdered sugar in a bowl. I just set a wire mesh strainer in the bowl, dumped the sugar in it and shook it into the bowl, Again, it's fussy, but it makes it easier to mix and it comes out better.
Melt a half stick of butter and pour it in the sugar along with 2 tablespoons of orange, lemon or lime juice and a teaspoon of vanilla. You can also add a teaspoon of grated zest for a little more flavor.
Stir it all together. It won't seem like that little bit of liquid will be enough for all that sugar, but it will. Do this by hand with a wooden spoon. If you do it with the mixer, it will A.) cover your kitchen with powdered sugar
and B.) whip too much air into the glaze making it brittle. Pop the cake out of the pan on a plate (CAREFULLY, it's really fragile at this point) and then drizzle the glaze over the top.
Now the really hard part: Let it sit for several hours so it soaks up all the soaking glaze evenly and the other glaze sets. Overnight is best.
So there you go! Good luck with the party and make sure you let us know how it turns out. Preferably with photos!