Hard flat surfaces:
The best surface is a flat hard surface such as flat glass. Common places might be a glass desktop, stove top and kitchen bench. These items may not be the best as the spinnning action can leave a mark on, especially is spun at a high RPM artificially. Spinning a top with your fingers will rarely mark a glass surface if the ball is clean and free from any debris.
Dished glass surfaces:
Purchasing a magnifying beauty mirror is a great way to get a surface that is dished or concave and will keep the top spinning in the center due to the curved surface. Desire3D supplied such concave glass in the form of a dual sided concave glass that are a perfect size to sit on your desk and showcase the top. The glass comes with a beautiful polished brass ring that surround the glass and assists is stopping the top flying off when trying to spin it as fast as possible.