I really appreciate the help! Jan, that tutorial is super and I'm sure it'll be a big help as I do more garments. Although I had a certain amount of bulk in the set in sleeve seam, I somehow managed to get the project finished and it looks pretty OK! Next time, with the help of this tutorial, I'm sure my sleeves will be set in much better.
Salmonmac, I agree about the mattress stitch joining. I tried that but wasn't actually doing it right so I still wound up with the bulky seams. BUT, knit, live and learn! Next time it'll be better. Meanwhile, the sweater (for my 80 year old godmother) will be enjoyed anyway!