Kiltmadoc, a lot of Cruisers say the same thing, set and forget, which is why they don't opt for high dollar halyards. This couldn't be farther from the truth. If you want set and forget, you need to eliminate stretch, which would actually require you to buy the high dollar strings.
The less a jib sheet stretches, the less you'll have to re-trim when the wind picks up. Same with a halyard. When the wind speed picks up, the extra pressure stretches the halyard and sail material moving the draft aft and creating a more powerful shape. Just what you don't want.
If you're worried about cost, look to see if your hardware will accept 5/16th halyards. But yes, 3/8th would work just fine, and for cruising (I equate cruising to not caring about sail shape) then sta set would be fine. Sta-set-x would be better, and warpspeed or endura-braid would be something you can see the difference.
If you have money to burn any SK-90 core would work, but that's $6.40 a foot. Overkill if you ask me. I do think you'd be very happy with Warpspeed (samson- $2.60/ft) or endurabraid (NER- $2.60/ft).
Merit 25 # 764 "Audrey"