@anarcat Do you have a Staples with a print centre near you? Your experience may vary but I find that some can be very helpful despite being a big box store. I had a few experiences where the employee would let me see various weights and types of paper and print samples until I got what I wanted. I didn’t have to be a sweet talker. 
Bonus: I met one of the original hosts of the recently cancelled TV show Daily Planet at a Staples. Jay Ingram didn’t know me but I waved anyway. However, he didn’t notice me at all because he was super angry about his printer and possibly bad customer service. His face was visibly contorted. I guess everyone has a bad day. 
Unfortunately, all the Staples in my area closed. Maybe they do mostly online sales now…