Why worthwhile? The Tre Cime di Lavaredo (Drei Zinnen) is something you have to have seen! Tip: start on time in the morning (08:00 at the latest) to avoid the (mass-)tourism (and stay ahead).
Why worthwhile? Impressive (climbing) tour straight through the pointy Cadini mountains.
Why worthwhile? Quiet surroundings with beautiful views of the surrounding area.
Why worthwhile? A lot of diversity; from the well known tourist attractions to the more quiet city park and the narrow quaint streets. Of course you won’t see the whole city, but you will get a great general impression of Rome!
Why worthwhile? Very beautiful “panorama mountain” at reasonable height (> 2800m) with a relatively easy climb.