Knitting

I’m confused as to why thinner knits would be more office appropriate than thicker knits. What’s the difference? I think what matters more is pattern (no explicit colorwork, no super-open lace that leaves little to the imagination, etc.). It sounds like your office is pretty casual so I’d imagine that no one will bat an eye at what you’re wearing as long as it isn’t flashing too much skin and doesn’t have swear words or whatnot on it. I have a bulky-weight sweater, the popular one with owls on it, and I’d wear it to the office in a heartbeat if I still worked in one.

Also, never underestimate the value of a good cardigan, perhaps with a shawl collar, in an office where men control the thermostat.

There's a couple women in my office that rock a knit shawl or poncho year round and nobody is bothered by it.

I'm not local to you (so social conventions might be different) but if the dress code is casual I think as long as you don't go for a pattern that is actually offensive or anti-corporate you will be fine. Even advice like no bulky yarns sounds like it is rather based on traditional office dress, where you would want something that can be worn under a suit jacket.

One thing I would suggest you take into account is how easy to take it off it will be. You won't control the thermostat so you might find yourself adding/removing layers to maintain comfort. You might also might find yourself wanting something in the summer too, if the site is air conditioned.

Generally speaking, v-neck sweaters are great to wear over button-up shirts. Cardigans in every form are great as well. Turtlenecks are always welcome as well. I have a lace blouse that I frequently wear, with something underneath of course.

As general hints: I feel like neutral colors are considered to be more office appropriate, also you should opt for full length (not cropped) and (short) sleeves.

The consideration of yarn weight might come from the presumption that oftentimes bulky weight garments are also more boxy, oversized and casual? That highly depends on the pattern and garment design. There is no right or wrong weight.