Access the Internet even if another PC in the home is already using the internet. Sit on the sofa with your laptop and open files on a home office PC, or print documents on another connected PC's printer.
Every phone jack can double as a home network connection.
Get everyone online at the same time. Whether you choose wireless or phoneline, you can't lose. They're both easy to install and require no new wires. Both enable you to share Internet access, as well as share printers and files. Phoneline is great if all your PCs are near a phone jack.