I flew stretch from ATL to DEN and DEN to ATL. I liked getting my favorite seat, 2C, on both legs but I'm not sure it's worth $25 each way. I only fly frontier 1-2 times a year to visit family in Albuquerque so I doubt I'll have status anytime soon.
The extra leg room wasn't even that great. I'm 5'9", I didn't use any of it. And I still had to pay $50 to check 2 bags on the way back, plus $6 each way for TV....that should be thrown in for Stretch, even if it meant it costs a little more.