I write character driven stories, and most are romantic-centric, meaning the feelings developing between certain characters serve to drive the story forward. Most of my books include scenes of intimacy when it serves to explore character development, but the heat level of those scenes varies.
Here is how I define heat levels:
No Heat : The characters might kiss.
Low Heat: There will be one or two scenes of intimacy, but it’s mostly flowery text or fade-to-black, with a big emphasis on the emotions and thoughts rather than the act itself.
Medium Heat: (I think this is pretty standard modern romance fiction heat level) There will be a few scenes of intimacy. Big emphasis on the emotions and thoughts, but the scenes are more descriptive, and may use more mature anatomical language.
High Heat: Same as Medium Heat, but more of it, and the intimacy itself is a major driving factor in the plot and character development. There may even be some BDSM.