The neck is one of the most favorable areas to do liposuction on. However, the degree of skin tightening can be variable. A facelift will usually give the best result, but in many patients, liposuction only is a reasonable approach.
See an experienced face lift surgeon to tell you the answer. Liposuction works best for a "double chin" in a young person. If you have saggy skin you will not be happy with liposuction.