I finished the top first.
Here's how I finished the seams. The one on the left is "wrong sides together" and sewn in about a 1/4 inch seam. The one on the right has been trimmed down to about 1/8 of an inch.
After I iron the seam to one side, then I iron it "right sides together" and stick a few pins in to hold it in place, with the stitching running along the fold. Then I sew another 1/4 inch (or maybe 3/8) seam, with the right sides together, encasing the raw, trimmed edges.
I couldn't do a French finish on the crotch seam of the pants because it bends sharply. Here is a french seam (the lower one) compared with the seam that I sewed a double line of stitching on. I am pulling away the threads that fray madly. I will trim those but they will continue to fray whenever I wash the pants, until they reach a kind of stasis. C'est la vie.
Speaking of the pants, here they are before I have installed the elestic/drawstring combo through the waist casing. They look huge! And they look like those silly basketball shorts. Sorry if anyone reading this admires basketball shorts but I think they look silly.
Here I have completed the drawstring waist and tied the strings in a bow. They'll sort of look like culottes when I wear them, I am thinking.
See how madly the cut edges of this fabric fray, even when I've hardly handled them.
I haven't finished the robe yet but I thought I'd bundle all three pieces up to see how small they will pack. That was the point of this exercise after all - to make something that packs up pretty small. I am happy with the size of this bundle.