Cory Silverberg is one of my favorite sex writers and if you don't follow him, you definitely should. This is a small part of his response to someone who says they're a virgin and doesn't know what to expect the first time they have sex. "Even after you do get to have sex with someone else, all you'll know is what that sex was like. No two bodies are identical, no two people are the same, and so no two sexual encounters will ever feel exactly the same way. If you're sober and at least a little self-aware, sex will be different with every new partner, and it can be completely different with the same person from one encounter to the next.
Sex can be a cookie-cutter experience, you could do it the way you ride a bike, shower in the morning, or get ready for bed, meaning more or less the same order of things, the same thoughts, the same feelings every time. But good sex, great sex, is sex that begins without you really knowing where it will end. It has boundaries and parameters (so good sex doesn't mean anything goes, nor does it mean you shouldn't plan) but it is as free of expectations as any encounter with another human being can be."
Cory wrote this response a while back and is still wondering what exactly the right answer would involve. Your best time? Your worst time? For me, above is one of my favorite parts of his reply, but there's so much more.
Personally, the first time I had intercourse (which is often what people want to know about) it felt like a totally mechanical experience–someone put their penis in my vagina–and it was a total let-down. Also, it didn't hurt and I didn't bleed and it wasn't the least bit exciting, except for the getting-it-over-with part. It was only after I had sex different times with different people that I understood all the subtle different kinds of things I would and could feel. That's one reason I wonder at the wisdom of having one partner in life–the one you marry (aside from the sexist, homophobic, moralistic, shaming aspects involved in those teachings). But I digress. Please read his full response here and weigh in if you'd like.