I've upgraded DAY-DEN on exPlus... nearly 3 hours. The booze is nice, but what I really appreciate is not having to twist my shoulders for the entire flight. I always end up with a sore neck whenever I don't upgrade and the seat next to me isn't open.
That said, I still usually save the e500s for lunch/dinner DEN-SJC/SFO/LAX flights on my beloved 757.