There was also a presumed Least Sandpiper that did not look or act like a Least Sandpiper on the river beach. He was all alone and hiding in the tidal plants for the most part. Most Least Sandpipers I see are on the rocks or at the water's edge with the Semipalmated Plovers or with a bigger flock of peeps. The bill seemed slightly longer, fatter and less curved and he seemed a little larger, definitely more upright in posture and when feeding had a more tippy, bent-over look than the typical hunched-down appearance of a Least Sandpiper. I took a bunch of pictures and put up 10 of them in a Flickr album. So, while it most likely is a Least Sandpiper, it has some markings which make me wonder. There is a bit of that "J" look on the front of the face with dark reaching all the way down to the bill. While there is no obvious lighter look to the lower bill - there is a bit of reddish-brown tone under the bill that shows up particularly in picture #0937. I have no idea about the length of the toes but there are a few pics with marginal views of them. Many more pictures are available but I don't think they'll add much more info.
So for what it's worth, I thought it best to share rather than just assume a Least Sandpiper.