You can drive up to the top, enjoy the beautiful views (without doing the Grouse Grind, or paying for the gondola), and enjoy a picnic in the summer. There are hikes all up the mountain, and you can see quite a bit without paying for anything.
The views of Vancouver, and the surrounding area, are priceless (notably, at sunset). If you drive up in summer, you'll find that there's not much going on at the top...except for the experience you will create there.
Be aware that most rental cars/cars in Vancouver do not have snow tires. Snow can stick around until June.