If you are using a pricey rug in your entry. Do what I do. Protect it with a small washable throw rug. Covering the spot most traveled on a daily basis. Then for special occasions stow the throw rug in the closet. Meanwhile, the better rug will stay clean. No space for a rug? Paint an interesting design on the floor. There are a wide variety of stencils that you can use if you do not consider yourself an artist. Be sure to use a sealer topcoat to ensure your painted design holds up to heavy traffic and will clean up easily.
If you choose wallpaper with lots of pattern, you will have very little need for pictures or artwork. When choosing wallpaper, don’t assume that a small foyer should be papered with an equally small printed design. Some of the prettiest foyers I’ve been in, were small ones, where the paper chosen was large scale and very bold. The effect was wonderful! The entry is the perfect spot for tromp l’oeil. Possibly a mural of a Grecian urn or a large topiary.