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.
Use an oversized urn with a sprawling palm tree. A 19th century Victorian Hall Tree in the right home would be beautiful and functional. An antique store would be the best place to look for a piece like this or better yet an auction or estate sale. Use a pair of corbels topped with marble or a pair of iron supports topped with glass for a shelf to hold a vase of flowers, keys and mail.