Rib Eye or FIllet

15 pounds of tenderloin makes my wallet...make that my checking account nervous!!

I have done a whole tenderloing before, really not that hard as long as you tie the "tail" up in order to get the thickness consistent, assuming the whole crew wants roughly the same "wellness". If you've got some "kill it good" red meat eaters, just leave the tail untied and cook to 125 internal on the thick end for a nice medium rare, and as you move towards the tail, the more done it will be.

HOWEVER, my carnivore eating family would need more like 10 oz per person, so I'd be looking at a 2nd mortgage.

Never done a Rib Roast, I'm sure you'll get some advice.

IMHO, 15lbs is way to much. I'd go with the ribeye but cut it in half. Some may want well to medium well.

Mike

Personally, I think I would go with the roast, either the rib or a chuck...All though I have done a venison loin with GREAT success! But feeding this many, I do think a roast / roasts would be a better route to go, being that it would take less attention and, they are more forgiving.
To address your questions regarding temp. time and seasonings:
A roast should go at 350 F. figuring, about 25 to 35 minutes per lb. If you do cook tenderloin, it should be hotter and faster…Maybe 450 F. and only 8 to 10 minutes per lb. Either way, I would set up for indirect with a drip pan to collect those great juices for an au jus”
When temping beef roasts:
Med. Rare is 145 F.
Med. is 160 F.
Well is 170 F.
I would go with two or three smaller roasts as opposed to larger:
1)) It will take less time for the cook.
2)) You could easily have them at various stages of “doneness”.
And lastly, you could even do them with different seasonings!
I while back I saw this on the forum. I haven’t tried it yet, but it sure sounds good! So I’ve included it here.
It was to be thin sliced and served as sandwiches with a sauce, but I think the marinade would be great with any roast beef…No matter the serving and really do want to give it a try!

BOURBON-MARINATED "PIT BEEF"
(Drunk & Dirty of Smoke & Spice)
North Portage Smoke-Shack
From Cheryl and Bill Jamison, "Smoke & Spice"

For the marinade:
(This is enough for about 15 lbs. of beef roast....Adjustments should be made for lesser or larger amounts)

2 C. soy sauce
1 C. bourbon
1/2 C. Worcestershire
4 T. brown sugar
1 t. ground ginger
8 cloves garlic, crushed
1 C. water

1)) Mix the marinade and add to the meat in a baggie. Coat well and place in the fridge, for 4 to 24 hrs.
2) Before cooking, remove the meat from the marinade. Sprinkle with kosher salt and black pepper.
3) Set up your smoker for cooking. Using my Big Green Egg, I set up for indirect cooking, putting in the plate setter legs up, with a drip pan sitting on the plate setter. I used hickory wood chunks to add smoke flavor, and brought the temperature up to 250 degrees Fahrenheit.
4) Smoke the meat at 250 degrees for about 45 minutes, then raise the temperature to 325 degrees until the internal temperature of the meat reaches your desired level of "doneness". Rare 120 F. Med. rare 145 F. Medium 160 F. Note: I normally don’t like my beef very rare, but for this recipe, medium rare (and even medium), thin sliced meat comes out very tender and juicy.
5) Pull the meat from the smoker, wrap in foil, and let rest for 10-15 minutes.
6) Slice the meat very thin. Serve on a hard roll with barbeque sauce or serve it up like a "prime" with sides of potatoes, veggies and a salad.

OTOH, here are two spice blends that I have found to be very tasteful on either beef of pork. I put the rub on and then refrigerate for at least an hour or two.

SPANISH TOWN
2 T. prepared curry powder
1 T. sugar
1 t. ground black pepper
1 T. dried leaf thyme, crumbled
1 T. onion powder
2 t. garlic powder
1 t. salt
1/2 t. ground red pepper (fine ground cayenne)

ALBUQUERQUE DRY RUB
1 T. coriander seeds (or 2 teaspoons ground coriander)
1 T. cumin seeds (or 2 teaspoons ground cumin)
6 T. chili powder
1 T onion powder
2 t. garlic powder
2 t. dried oregano (Mexican, if you can find it)
2 t. salt
1 t. fresh ground black pepper

Enjoy and have fun…
Spuds