We spent about a day and a half in Cinque Terre, and on our full day we hiked between all five towns with the most incredible weather. I felt like I was in paradise. There was the crystal clear water below, the bright, colorful flowers and rows of grapevines lining the trails with constant views of the cliffs with waves crashing into them below. Though I obviously haven't been everywhere in the world, I can confidently say there is no place like this.
Also, did I mention the hikes are pretty hard? Courtney and I definitely got a good workout in. I think it took about 7 hours total, stops included in each town for a picnic, souvenir shopping, etc. but these trails aren't a joke. If you're not into hiking, there's a train that runs very frequently between each town, so you can still easily see it all! However, I'd definitely recommend at least doing one leg of the trip - the views are even better from the top!