I'm definitely not old (~30), and my preference has generally been my age +/- 5 years.
As I've gotten older, I've noticed that my sexual attraction has migrated from being solely based on physical attributes to being partially based emotional connection, intelligence, passion, etc.
I think it's also important to note that an individual's "peak attractiveness" can occur at different stages of their life.
I disagree that it can only be romantic attraction.
For example, I can find a random person attractive if they're displaying a skill they're proficient in, talking passionately about a subject they're knowledgeable in, or freely enjoying themselves. And all without feeling any kind of romantic inclination towards them.
It's primarily sexual despite the fact it's not necessarily physical