UPDATE
I went to a Best Buy to take a look at ebook readers. Here's what they had available for some hands on:
- Sony PRS-350
- Sony PRS-950
- Kindle 3
- Kindle DX
This was a pretty good set to compare with my 505. I walked away with some surprising thoughts:
- The 5" screen is too small for my taste
- Not a fan of the silver Sony models - my 505 is dark blue
- The Kindle's screen being nearly flush with the black bevel is very nice
- The Kindle's mode of selection - moving the highlight up & down a list is simple and speedy
- The Kindle's keyboard seems almost totally useless to me
- The 7" screen on the PRS-950 was a *great* size for reading on medium zoom and held at more of a distance
I was really surprised at how nice having a slightly larger screen is (7" compared to the 6" screen on my 505.) The problem now is the PRS-950 is definitely beyond my budget so I have to pretend I didn't see & like that one

It doesn't look like there are any other 7 or 8 inch e-ink pearl screens. The next closest would be the Kindle DX, but that's *too* big for my needs and too expensive. I guess I'm back to my original thought - a 6" screen is the right size at the prices they go for.
Now my choice is definitely between the Kindle 3 for $139 (readily available) vs. the Sony PRS-650 Reader for $229 (out of stock for the most part.)
EDIT
carpetmojo: I didn't even have to talk to anyone - just found the eReaders display and had my way with them.