I'm pretty boring - I stick to black and grey socks. I wear the black socks with black booties and with leopard booties. I wear the grey socks with my blue booties, and sometimes with the black booties if I've run out of black socks, and I'm wearing jeans.
I prefer socks with wool- cashmere blend because I find they keep my feet warm, and they tend to wear better. (Smart Wool is toasty but inevitably I get a hole before the season is out). It sounds expensive but I've been able to find cashmere blend socks at Target for not too much money and that hold up pretty well.
I just ordered a bunch of socks on Amazon this week since it is time to replace some of the older ones. I went first to Target but didn't see cashmere blend. I went to Nordstrom & Macy's site but couldn't find a way to filter by cashmere blend, so I checked Amazon and found a bunch. I stuck with grey and black again but couldn't find plain ones. I ordered stripes and argyle and dots and I think I may have ordered a red pair just to be different. I forget now. Package has yet to arrive. I simply did a search on cashmere-blend socks, and then ordered a few different brands. I can let you know better once they arrive!