Most of my stories are based on my real-life sexual experiences,. So yes, the memory of those wonderful experiences turns me on powerfully.
I've written 2 or 3 fantasy sex stories, an yeah dreaming up sexual adventures that I've never actually experienced is also a turn on, else why would i have dreamed up such adventures? But maybe not as much a turn-on as sweet memories of the physical and emotional pleasure of my past sexual adventures.
I think my favorite story is the one of how i met my gf Tina 9 years ago. I told her I find her very sexy. She turned ne down, not interested in lesbian sex. But the next day, she told me she had a very erotic dream about me the night before, and she wanted to change her no to a yes. We both had some of the best orgasms of our lives that night. We are both bi. We both love cocks, BIG cocks! But we also still have regular "pussies only nights - no cocks allowed." Just the two of us. Those nights are still as magical as that first time 9 years ago.
Writing about that, those memories, especially that first time with her, are a HUGE turn-on.