This. Basically, if you are meeting during the work day and you work in a professional environment I would just show up in what you wear to work. Just don’t forget your belt at the gym that day…like I did today.
Are you meeting on a work day? I would wear whatever is appropriate for your current work, perhaps a notch dressier. Your goal is not to show off how much you can dress up. You’re taking time out of your normal work to go meet him to discuss something. He knows this already, or at least should know it.
If you normally come in jeans and a button-down and suddenly show up to work in a suit and tie and have a long lunch, it raises suspicions, which could get you fired in some places (some places will fire you if they discover you looking elsewhere), or at least put on an internal watch-list.
If you’re taking the day off to meet him, then I think the suggestions about a suit with open collar are sensible, or perhaps nice trousers and a sportsjacket, though I get the sense (based on little data) that that’s your normal kind of attire.
If you normally wear a suit to work, then don’t dress down, though.
Turning up in a full suit in a coffee shop even though it is a business meeting looks definitely weird. You can opt for a business casual attire that includes slacks or chinos, shirt with/without a tie and dress nike shoes. Avoid wearing polo shirts though.
I had an interview in Silicon Alley and overdressed. I didn’t think it was possible to overdress but wish I asked the CEO about what he was ok with me wearing to the interview.
It was a super trendy place. I could have shown up in vans / t shirt.