As crazy as it sounds, if you rent a car, and then you have a place to stash your bag, then 6 hours may be tight. The Phoenix Airport is big, and getting a checked bag takes time, and getting to the Rental Car Center takes time. Getting your car takes time and then doing it all in reverse when it's time to fly out takes time. And depending on too many factors to list here, traffic could be nasty, or not, and take time too, not to mention the very real possibility of taking a wrong turn. Just some logistics to consider. Not to mention getting back through TSA and to your plane, which at PDX has taken me anywhere from 5 to 45 minutes.
That said though, hell yes it's worth it. There are some great clubs in Phoenix. An afternoon visit to HiLiter is a must. Christie's in Tempe (with a hotel directly behind the club, a Ramada I think?), is a good choice. And Bourbon Street Circus has top rated talent relative to dancer looks. And I truly believe a first time visit to HiLiter in the afternoon can result in a grand time. Those girls don't care if you are passing through or not.
As far as I know there are NOT lockers available at the Phoenix Airport like I've used in Vegas.
I think if you can arrange a flight into PDX around noon, you could be at HL by 2 or 2:30. Then spend a few hours there, before heading back to the airport around 5:00 for an 8:00 flight is realistic. If you could land around noon, you could follow up a HL visit with an evening trip to BSC or Christie's in Tempe (not the Phoenix Christie's) and fly out the next morning.
In the heat of the summer traffic may not be as bad around 5:00, rooms are typically less expensive, and often fewer girls are dancing. But last week at HiLiter the talent level was great and there were lots of girls (easily over 40).