The Costco choice steaks are sometimes tricky to pick out. Like I'd see them pack two really nice and marbled ribeye steaks but the third one didn't have enough fat for my preferences. You may have to dig around to find a perfect package set. Otherwise you may have to look at their prime grade steaks.
I've only had the tomahawk once and it was pretty good. Normally, with something that thick I'd put it in the oven and slow cook it for about an hour and then finish it off on the grill with a quick sear. But I decided to try slow cooking it in the smoker this time around and then finishing it on the grill. The added smoke flavor made it quite interesting gave it a beautiful aroma.