Wonderful manly hats! I love doing hats too. They can be addicting.
The scarf for you BF's father is a very nice thought. I agree that a K1, P1 rib would look an awful lot like stockinette and not be so many stitches or use so much yarn as the circular one, although it is lovely.
Hygiene Mama, I didn't use a pattern for the hat. I followed the recommend number of stitches per inch, measured his head and cast on the appropriate number of stitches. After about an inch of so (just plain stockinette, I knit it in the round so it was just knit stitches all the way around) I added the green yarn knitting with both strands for one full round, then dropped the brown and knit with just the green for three full rounds, and then picked up the brown and knit with both for one more round before clipping off the green. Then knit knit knit knit knit in the brown for a few more inches and abbbbbout halfway up the hat started knitting together 2 stitches every 15 stitches or so. I tried to keep in mind where in the circle those decreases were made so I could sort of spiral it out . After about an inch and a half of decreases every 15 stitches in the brown I added in the green again for a stripe, back for a bit more of the brown, then dropped the brown for good and finished off in the green. The green yarn was a lighter yarn, and at about that point I switched to double pointed needles. Then I just did one or two decreases per needle until I had about 20 stitches left, fed the yarn thru the loops and pulled it all together and tied a knot and threaded the tail into the hat. =]
I'm tryin to get the decrease rate just right. At first it all bunched up and then there was a little poof tip. Hopefully soon it will be juuuuuuust right