Costco’s steaks are amazing. Neither of us knows how to grill, or cares to know, so I do it on a Cuisinart electric grill. It’s delicious.
As for tipping, having been a waitress during my college years I think I tip pretty well. Base is 17%, then higher for great service.
I learned a dirty little secret from a meat distributor when I worked at a high end steak house in college. The secret is only about 10% of beef is grade A prime with “abundant” marbling, and all of it goes to commercial sales and restaurants. The public does not have access to that meat. That is why no one can never seem to get that restaurant taste at home....
When it's not grilling weather, the way we do steaks is with a large cast-iron frying pan. The big trick is to let the steaks come up to room temperature before cooking (otherwise the center will be raw instead of pink). Cast iron is best because you can get it hotter than non-stick pans, and it retains heat better.
Put some thin pats of butter on the steak (not in the pan), and flip the steak onto the pan (butter side down). After a two minutes (more or less depending on thickness) put some more butter pats on, and flip the steak (use tongs, not a fork). You will get a perfect steak.