I've run Mt. SAC and Holmdel, and I'd put Mt. SAC ahead for both toughness and fame. Comparing the 3M/5K courses: There are two tough hills at Holmdel (start, Bowl), and they're done by mid-race. If you cruise the opener, you're pretty much okay the rest of the way and can attack on the Bowl--it's flat and down after that, and that twist-and-turn section through the woods in Mile 3 could even be called fun. At Mt. SAC, there are three pretty much evenly spaced hills, each of which is as tough as either of the Holmdel hills and one of which (the Switchbacks) is the toughest of the five. The third one (Observatory) is in the first half of the third mile--a bad place. And just for kicks (or the lack of them), the final 100M is a mild but steeper-as-it-goes uphill, too. As for fame: correct me if you know different, but I never hear about Holmdel in CA, but I do hear about Mt. SAC in the East.