Today I went up Old La Honda, made a few wrong turns and ended up at the base of Old La Honda again. So I figured what the hell, I'll do it again. So I did. I figured out the stopwatch on my computer by the second time, and got a figure of about 36 minutes (from the turn off of Portola to the top). I'm sure that puts me in the "mall walker" speed category.
The descent down Skyline and 84 is worth it, though.
Here's a quick panorama (comprised of about 13 images) I shot at the top the first time. The way the fog was rolling along was really pretty, but doesn't translate to film--err, jpeg, very well.