For duvet covers I don’t think you can beat the IKEA Ofelia Vass sets. They have a seersucker type texture, so they’re forgiving of wrinkles and don’t require ironing. I’ve hosted for 4 years and only had to retire one set so far.
I like the Threshold 300 ct organic cotton sheets from Target, but any white sheets on sale at TJ Maxx/Marshalls, etc mix well together. I prefer 100% cotton and just try to catch them as soon as the dryer finishes to minimize wrinkles.