All the things that are most fun to do together as a couple -- traveling, even if it's just going to the next town over to eat lunch and hit the antique shops; talking about your beliefs and your dreams in life; reading books or watching movies together -- also help you both in terms of expanding yourselves and grabbing hold of opportunities. You, especially, introduce your partner to new ways of being that surprise and delight them, and that definitely expands their horizons for the rest of their life, regardless of how long your relationship lasts. Risk-taking could be a focus between you -- going skydiving together isn't out of the question!
You can keep things simpler by taking a class together or going to see plays and discussing them afterward over a cup of tea. You both find a lot to like about the way each other's minds work, but your partner, especially, gets a lot out of your particular brand of intellectualism. You feel comfortable with them, as if they just get all the ways that you look at the world, and the things in your thinking that make you you.