Yarn dilema

I had planned to make two IHS, one with Noro Kureyon and the other with Cascade220 but after casting on and knitting two repeats i was unhappy with the result. I like my scarves to have quite a thick, close texture and the result with both these yarns was quite open. I tried again with 4.5mm needles but the result still wasn't to my liking. I don't want to decrease another needle size as this would make the scarf too narrow, so i would need to use twice as much yarn by doubling the width.
I figure i have two options look for a aran (worsted weight yarn) and use 4mm needles but double the stitches and width or use a chunky yarn. I am open to both options but unsure how to estimate yardage of chunky yarn. The first option is easy i will just double the amount as it will twice width.
In my despair of needing to start a new project i have already assigned the cascade and noro to other projects - cascade220 sophie and noro booga bag.
I quite fancy making the IHS in chocolate brown and have seen a blue faced leicester in sienna here which i quite like. I also like the idea of making it out a nice thick soft cotton and am drawn to the blue sky alpaca dyed cotton in espresso. I am going to have to postpone my IHS as i am on stashalong and not buying yarn now until August. I will be back when i have the yarn and am ready to start in ernest.