Brian,
I said "with respect to the Pacific Plate". If both the North American plate and the Pacific Plate were moving northwest with respect to whatever the refence is, but Pacific plate moving faster, then North America is moving SE with Respect to the Pacific Plate (I don't know the reference; some mantle hotspot frame? Some hotspots migrate).

First, thanks for coming up with that site: it is actually important for me to see that Guadalupe Island is defining a velocity really well: has to be continous GPS. Chuch De Mets either in his talk or in talking to him later, said that either this station stopped running or the data are not provided.

OK, what I (and I think you) are interested is relative motions between plates. That was again very interesting that Hawaii is moving so much differently. But there is not 20 mm/yr motion or whatever of deformation between Oahu and San Nicolas (there is 3 mm/yr according to De Mets). I had not thought of this before, but it must be because the plate motions are on a sphere (OK, oblate spheroid). There is a pole of rotation about which plates rotate. De Mets solves for these motions and the comes up with relative motions across plate boundaries. For Pacific - North American motion, this motion is larger at the latitude of southern Baja than central California.

I'm not checking, but may be about 52 mm/yr in south and 48 or 50 in central California-Nevada-Utah.

Note also that a couple of the stations in and near Hawaii volcanoes national park are moving very differently from the rest of Hawaii and the other islands. This is because of a gravitational collapse of the south flank of Kilauea. There are big active faults scarps and big earthquakes from this: A M7.5 in the 70s (1975?) and a M8 in the 19 century, both with tsunamis. The 1970s tsunami washed away 10 campers, but most of them were washed into a fissure and survived (I think 2 or 3 died).

Collapses of the islands occur every couple or few hundred thousand years, Chunks of coral up 300 m-high on one or more of the islands (Lanai?) indicate giant tsunamis. You can see the debris fields of some old mega slides on Brian's link or presumably Google earth.

OK, Long post.

Chris