Most of the modern ones do - anything from the IQ1-IQ4 has a good preview screen, for live view specifically you need a CMOS sensor based one like the IQ3 100 or the IQ4 150. The CCD ones technically do live view but it's really not good. So this only works for backs that are fairly expensive still...

Close to West Seattle! I'm in the North Seattle area and walk around near the water there a lot.

ah right on, thanks for the info