Lurking, but had to add my favorites:

- All-time favorite is Victoria Peak in HK. That, however, is a little silly in the LUV thread. I'll start at the FS or Upper House and go all the way to the top. Always hot/humid and beyond category steep. I'm gasping and completely incoherent by the time I get to the top. A perfect run, but an 1,800ft hill from sea level .... that tends to get your attention. Perfect to determine you max HR

- I really like the horse trails outside of Palo Alto on Sand Hill Lane. This would be out of SJC and you would need a rental car. Great if you're stuck in Silicon Valley.

- Also silly in the LUV thread: Catalina Island. You need a boat to get to this place from Long Beach. No such thing as a bad run on Catalina, but everything is up. The marathon is considered an ultra due to the elevation gain/loss.

Of course, there is always going up the hotel stairs and then taking the elevator down. Repeat ad nauseam. This can be awkward -- gasping for air and sweating in the elevator can elicit stares. But in smoggy cities, it can be the only choice short of the treadmill.