I love costco for towels too. Lately I've been buying just white. It seems that my daughter's face cream and whatever our hockey billet boys use bleaches them out- so I have some really funky looking towels right now! We have a couple for our bathroom that are a light teal color- just because that matches the paint, but if I was buying new- I'd just buy white still- they always look nice & bright & clean.
We are NOT a "just for show" house in any capacity, let alone towels!
I do have some holiday hand towels that I put out in the main floor bathroom & kitchen, but we use them multiple times/day.