Bulky and heavy and not much room to pack.  This High Sierra wheeled backpack is a backpack that wheels were added to.

We ended up going with eBags TLS 22" Expandable Wheeled Carry-On which works great.  The ebags is a carryon suitcase and is shaped like a regular carry on suitcase, so it holds alot more and is very high quality. The wheels worked great and the pull handle very sturdy and easy to use.