I've gotten lots of help from the knitlist folks on my sweater question. Some urged me to try a neckline ribbing to pull the neck in, and others said frog it. Comparing the measurements of this sweater with my other sweaters, it's just too big. I think the problem comes from adding sleeve stitches to the back neck stitches and increasing for the depth of the neckline. The back neck jives with my measurements, but the sleeves and row increases brought the neck down too far. It looks like a large square neck opening. I could do a deep ribbing, with double decreases at each corner, but I don't think I'll like that look.
I think if I go with my neck circumference measurement and cast on all the stitches at once I'll be happier. I'm going to leave the other sweater on a string and start a new one. Then I can compare the two.