We've stayed at two places where we left early - The Fantasea in Atlantic City, and Pacific Shores in Nanoose Bay, BC. We left Fantasea after four nights because we hated Atlantic City and the resort, which was going through a renovation, but our room was horrible - in fact the whole resort was well below our usual standards. We left Pacific Shores after six nights because my husband was bored with Vancouver Island and wanted to go home. On both occasions we had driven in, so leaving early was an easy option. We just checked out early, the resorts don't care as they've been paid for the whole week.
We also arrived a day late to Renaissance Aruba because we couldn't get a flight. We notified the property that we would be a day late, there was no problem and our room was ready when we arrived. If you're arriving late it is essential to let the property know so they don't relet the room.