Go to a real furniture store and ask to see their catalogs with office desks in them. Most better companies sell desks but most furniture stores do not display them because they are hard to display. Many have credenzas, file cabinets and other pieces to match. Hooker, Stanley, and Lane are some that have websites you can google. Then look in the phone book ads for a furniture store that carries what you want.

Ikea has nice looking furniture if you are on a budget. Crate and Barrel is also good, pottery barn. I would look for all the stores I would normally go to but online.

It depends on what look you are going for. Executive desks and credenzas and files are sold at most furniture stores but these will run on the high side. If you want something more casual, office supply stores sell many choices.