I'm a strong advocate of not including the prequels in any viewing of the Star Wars movies, so my previous post in this thread didn't take it very seriously, and I apologize. My real serious response to the question of how best to experience all 6 movies as one saga would be this (two part answer):

1. Use the viewing order that places the prequels as a flashback in between episodes 5 and 6. That's definitely the best order that includes the prequels. You can make up your own mind about whether or not to include episode 1, I'm not going to nitpick about that detail, but at the very least watch 4 and 5 first and watch 6 last.

2. Part 2 of my answer involves the specific versions you should use. Since I don't watch the prequels, my favorite versions of choice are Harmy's despecialized, but if you are watching the whole saga including the prequels then those versions are not the versions you should watch. You need to watch versions that have been altered to fit better with the prequels. HOWEVER, and I must be emphatic about this, you should NOT watch the currently canonical release being sold in stores right now (with the possible exception of episode 5). For Return of the Jedi, there's really only one option for you and that's the 1997 special edition version. Anything after that includes the ghost change at the end and Vader saying "noooo" and those are changes that you and everyone else needs to avoid like the plague. For A new hope, there is again just one choice: adywan's revisited (in fact revisited would be your choice for everything if the others existed right now). For Empire Strikes back, you've got more flexibility since compared to the other two movies the changes aren't as much of an issue (even though the changes involving Vader's shuttle at the end are pretty friggin bad).

Enjoy the saga, whichever way you choose to watch it.