I have Showtime free for a year when one time i threatened to cancel which could expire sometime this year, even though all that time not one peep of viewing, and last month i received Stars free for 6 months which i do see a few times when there's nothing else on to see but get too repetitive with their movies, but i never get any discounts with HBO or Cinemax(although a i did get small discount once for Cinemax) but then again with all these free previews it doesn't make much sense in subscribing unless you're into their Series shows
If you've never seen it, I highly suggest checking out Spartacus. It's third (and final) season starts on the 25th. It's my favorite show on TV next to GoT.
Also, Starz recently launched Starzplay.com, (works just like HBOGo, etc), so you can watch all the previosu Spartacus seasons/episodes there. I do suggest watching the Prequel before Season 1/2, will flow a little better