It is kind of a crap shoot. If you go to a freeway, you can end up driving quite a ways on surface streets anyway just getting to the freeway or after you get off. For example, it is a few miles from LGB to the 91 freeway. However, once you get on the 91 you have a pretty straight shot right into the resort, especially if you are using the car pool lane from the 5. The downside is the 91/5 is a busy stretch of highway so you could hit traffic. It is closer to get to the 405 and then the 22 from LGB, but then once you get off the 22 you have to drive a few miles of surface streets again to get to the resort.
This is why most people that do it often say that going down Wardlow/Ball is just as easy. It is surface streets, which means lights, but Wardlow/Ball is only a semi-major street so it is not super crowded. I use to live right on Ball Rd near the Resort would frequently drive that way to see my then girlfriend (now wife!) in Long Beach all the time. It is a simple drive. I would not recommend going across Willow/Katella. There are more traffic signals that way and more traffic as well.
Hope that helps.