How long is long enough to stay in Cinque Terre?

The longest average stay in Cinque Terre, by travelers on this forum, is about 3 days maximum.
On this forum, a week in the CT would exceed what 95% of folks do.
But if you really, as you say, enjoy a "relaxed pace", then one week in the CT might be just fine for you.
It's good you don't have a car. You don't want one in that part of Italy.
If you think you just might be a bit restless after a few days in the CT, you could think about whether you want to try to go to Firenze (Florence) on the train as a day trip, if you haven't been there on a previous trip. It has more things to see per square foot than maybe any place else in the known universe.
But think about whether the travel time (round trip) would be worth it.
You probably don't spend time in Genoa. And since you don't have a car, you'll be limited to places you can get to by train.

The entire seaward trail system is only about seven miles long. You can easily round-trip it in daylight and have a beer/coffee in the four remaining villages -- and still be back to where you're staying I. Time for an early supper. It's not really a hike.

The entire seaward trail system is only about seven miles long. You can easily round-trip it in daylight and have a beer/coffee in the four remaining villages -- and still be back to where you're staying I. Time for an early supper. It's not really a hike.

Ed, I'll need to disagree with that. If you mean the 7-mile Sentiero Azzurro between Monterosso and Riomaggiore - which is the easiest, most popular of the C.T. trails - only two segments of that are currently open, and they ARE a hike for anyone unused to semi-strenuous climbing. A RT hike - even if the entire route was open- would also be 14 miles: no small feat for the average tourist. I am a reasonably conditioned hiker, and witnessed some people unused to outdoor activity really struggle on the more demanding sections of that trail.

There's no good answer for whether a week is too long or not. We loved the region, and could easily have spent a week there exploring the villages and lower/upper trails but again, we're trekkers who came prepared for a workout. Macnix, as it sounds like you're acquainted with a pair of boots, you'll be fine, and find plenty to explore. Check out the upper reaches of the villages where the majority of tourists rarely go.

My response here is mainly for the benefit of anyone who may get the erroneous impression that those 7 miles are a flat, easy walk in the park. They're not, and we were concerned for some distressed tourists who obviously underestimated their abilities.

You have 8 nights on the ground and I presume the last night you might want to spend it in Genoa to be closer to the airport.
I would spend 3 or 4 nights at most at the 5terre, that will allow for hiking the trails and a day trip to Portofino. Then I would spend the remaining nights in the seaside resort town of Viareggio and use it as a base to visit Lucca, Pisa, Apuan Alps (Carrara marble quarries), all of which are within 15-20 min from Viareggio. In summer Viareggio is full of night life too (the Cinque Terre at night is as quiet as a cemetery).
Then the day before the flight I would go to Genoa in the morning and visit Genoa the whole day. Next day fly home.
Florence is also doable as a day trip from Viareggio. About 1.5 hours each way.

Disagreement noted.

Replace 'you can' with 'I have'.

Make footnote: 'Thirty per day more than three days in a row kicks Ed's butt since he does not consider hisself especially reasonably fit.'

We have spent 11 nights in the CT over the course of 3 trips and will go back again in 2015. We love to hike and we LOVE the food in the CT. We have found the Trail #2, the Sentiero Azzuro that most people hike, is not our favorite. We hit the high trails. If you are fit and it appeals to you, buy a book about CT. hiking and explore somewhere beyond the Trail 2 March. You can daytrip to Portofino, Camogli, Lerici, Porto Venere, Santa Margherita. I have heard Genoa is worth a day and will do that next time. Check out the blog A Path to Lunch for more ideas in the region. They live nearby in Ameglia.

Carless is the way to go. Buses, boats and trains serve the villages and towns very well.

macnix,

How long is "long enough" will depend to some extent on what you want to do in that area. If you just want to do the obligatory hike of the Sentiero Azzurro trails, have a brief look at the five towns and chill out for a few days, three days is about right. You can be as active or relaxed as you want.

However, if you want to use the Cinque Terre as a "home base" for touring other places in that area such as Portofino, Levanto, Santa Margherita Ligure or Porto Venere, then more time will be needed. Transportation in that area is very easy using either the frequent trains or boats.

Regarding the Sentiero Azzurro trails, as others have noted only two of them are open at the present time, and that will likely be the case for the remainder of this year. Each of the four trails have varying levels of difficulty, and the one from Monterosso to Vernazza is the most challenging as there's a fairly significant climb at the Monterosso end. Once you're up to trail level, it's a fairly easy walk albeit a bit narrow in parts, and then there's a downhill portion into Vernazza. The trail from Vernazza to Corniglia is not quite as strenuous, but will require a bit of effort in parts.

When is this trip taking place? It's always a good idea to book accommodations in the C.T. WELL in advance.

Grazie everyone. Your comments are real helpful.

Grazie everyone. Your comments are real helpful.

I think a week is a little long and I love the Cinque Terre and have been there a dozen times. For most people 2 days of hiking would be good plus one maybe beach day. I would also suggest taking the boat to Porto Venere and would also consider visiting Portofino, Lucca or Pisa. That would almost be a full week.