Besides the various sources were we can get furniture models these days, you will find lots of design studios and marketplaces that offers premium furniture models for architectural visualization. A few years ago it was quite difficult to find premium models available online, but it seems like these online furniture stores are getting popular among artists.
One of those furniture stores is Design Connected that has a section on their website dedicated to selling 3d models of furniture, and among lots of paid models, you will also find an excellent collection of free furniture models. All models there are available in several formats like MAX, SKP, FBX, OBJ and others. For Blender artists, you will be able to use OBJ files with no significant concerns about compatibility. Just notice that some of those furniture models are quite large, and may add an extra load to your project.
Do you want to see an example? Take a look at this Monica chair created by the designer Mario Ferrarini and is available as an OBJ file with 32MB in size. This Monica chair is just one example of what you will find there.
