I cook & serve breakfast in black yoga pants & a chef coat.
http://a.co/39WYnlr I used to cook in a t-shirt then don an apron to serve, but I was ruining a lot of t-shirts with grease spatters. If I get something on the chef coat, I can flip the buttons around & hide it before serving

The only drawback is that sometimes guests remark, "Look at your cute little outfit!" which makes me feel like they think I'm playing dress-up or something. (Part of the trials & tribulations of being a young innkeeper)
When I greet guests, I wear anything from dresses in the summer (I prefer them to shorts) to jeans & a nice t-shirt. After check-in, I try my best to look presentable at all times but there's always gardening and painting to be done so guests have caught me covered in dirt, paint, spackle, and even cement mortar. I've had the misfortune of guests catching me in PJs and a bathrobe when I let the dogs out at 10pm & 6am in our private courtyard. It's a bit embarrassing, but it is my home after all..