This is by far my most popular design to date. I think the simplicity coupled with the versatility make it so appealing. The versatility being for a larger collar and a shorter vest wear with the longer side up and for a smaller collar and longer vest wear with the shorter side up.
This takes @2.5 skeins of Cascade Magnum. A Ravelry pal of mine Ronda of Main St Yarn Shop told me her mom just used 2 skeins when making one. The 3rd would be used towards reinforcing the armholes. Or you could scale back the size and use the extra for the armholes.
Needles: #19 circular 29"
Gauge: 1.25sts = 1"
One size fits all though you can use the schematic in the pattern to easily make adjustments.
Available as a PDF download. $6.50