I knitted this neat cap that has a spiral swirl effect using two strands of double knitting held together, I think an aran yarn or anything in that broad weight would also work fine. Its a very simple pattern and will be flexible to a broad range of yarns and guages. I made this in superwash, but for my next one I'll use aran wight wool and will full lightly then block for a smoother neater finish. I think it took about 100g or a little less, so a good stashbuster for an odd skein.
Using 5mm dp needles, cast on 100 stitches (25 per needle) and join without twisting.
Work 2:2 rib for 12 rows
Work plain stockinette for another 8 rows
Now start the swirly pattern:
Row 1: K2tog at start of needle, purl three, knit to end of needle.
Row 2: Knit two, purl three, knit to end of needle
Row 3: Knit one , k2tog, purl three, knit to end of needle
Row 4: Knit three, purl three, knit to end of needle
Row 5 and to finish: knit two, k2tog, purl 3, knit to end of needle
The last couple of rows will be almost all purl, but it makes sense when you get there.
Finish any loose ends, and wash and block lightly to smooth the shape (my pic is pre-blocking).