I write on the interior photographer page of my website about a trick with white balance.
“A big and busy space. Lots of grey carpet. I love grey carpet by the way. I can set my white balance just by using the eye dropper on the white balance tool in Lightroom and selecting the carpet.
If there is no neutral colour I use one of my grey cards to ensure that I have captured the correct white balance in the scene. The white balance that is specific to the lighting in the space I am photographing.
This is the starting point to all my digital image processing – getting the white balance correct. If not the colours are (or may) be out, and correcting the white balance can have an impact on the exposure, so it makes perfect sense to me to start off with the white balance and the exposure correct!”
Yes I know. Grey carpet. Grey furniture works just as well. And the beauty is that the carpet is illuminated by the dominant light source in the room.
One other tip – I take a set of images to capture the white balance, then take a picture of my hand before taking actual photographs, so i can easily tell when I get back to my office where the test shots end. This is more useful than it sounds – when you get back from a days shooting and have hundreds or even thousands of images to sort through little things like this really help.