I might show up in jeans.....if they are nice jeans as long as I have a nice shirt and shoes.
But, that is due to tradition, not Biblical command, so we need to try to make it less of a exclusionary point.
I have shown up in jeans, but normally I dress up at least somewhat. My husband always wears a dress shirt and often a suit (but not always a tie). Not out of tradition but out of respect for God. I don't judge fellow believers by their dress, although I do know people who do.
I usually show up in a sportcoat, slacks and turtleneck sweater during winter. Last week my wife and I showed up in jeans and I wore a solid color t-shirt.
Interestingly, last weeks sermon was from a missionary from indonesia. He was wearing what he called "Muslim" clothing. As he pointed out, it wasn't reall muslim, but what the people in that countries muslim "culture" would wear. He also pointed out that, just like many "Christians" in the US are not really Christian, many Muslims are as muslim as the Christians that only go to church on Christmas and, maybe, Easter, are Christian.
So much of it is just culture.