I think the title lacks a word. It should be "Sex:More of a physical or mental thing for men (or for women)?"
Because obviously, both sexes experience sex in different manner.
I don't know what is the answer of this.
Sex for me (and I am a female) is so much more a mental thing. I can't get until the end without getting in the right mood, and I can't get in that mood without good mental stimulation. Not so much the actions as the intentions. But then without the actual actions, all the intentions are useless.
I think sex is never meant to be separated to be just the one. It should be both. Because sex is uniting, it's making one from two. How then we can say it's only mental or only physical. If it's just mental- it's masturbation, if it's just physical- it can be painful and anyway, it's draining and empty. It should include all of our senses to be perfect. To be creative and full.
I think the idea behind sex, of course beside the reproduction, is to help us feel our souls. When I am in the mood I experience things in so different level. The shared passion, isn't it like you know what's in the other person's head and you're so eager to do it. To be hot is all about wanting to give pleasure and to expand. Yes, you of course require pleasure too, but the real thing is about giving. When you forget about yourself and it's all about the pleasure- that is the real sex. I don't think such intensity could be just physical or just mental. It's beyond that. It's pure heaven. It's the uniting of two souls and their joy of the meeting. It's the oneness of physical, mental and spiritual.
But still don't forget we can't experience without the support of our body and brain- everything passes trough them and is translated into the language of chemical substances. So in this language, even heaven is physical. But its reality and its essence and cause, its creative power and huge energy- it can be justified only by our Divine Soul. For sex is the most divine thing we're capable of doing in this world. We just have to do it the right way- with passion and self-denial. With love.