Pompeii or Herculaneum?

"unless he exhibits a great deal of interest"
Could you clarify, who is he? The 11 year old? Or the father?

Herculaneum is a great alternative to Pompeii when/if:
1. the weather is too hot
2. you don't have a lot of time
3. you have a bored 11 year old on your hands
4. you have a bored father of an 11 year old on your hands

My personal preference after three visits to Pompeii is Herculaneum, especially with an 11 year old. The site is way smaller than Pompeii and it has the feel of a recently deserted town which I think would appeal to a youngster. A lot of the buildings are relatively intact so you get a feel for what a Roman house looked like. Herculaneum was dug out of a pyroclastic flow so it is situated in a deep pit (you reach it by a ramp) and as you wander around you will notice buildings eroding of the sides of the pits. No theatre or arena but lots to see. The modern town is situated right above the ruins and Vesuvius looms . If it sparks an interest you can always do another trip to Pompeii. Two hours would be plenty to see Herculaneum and it will probably be hot in the pit.

When we left the site, instead of going up the ramp, we took a tunnel that cut through the flow..... which again I think would appeal.

Sorry for lack of clarity -- the 11 year old's interest would probably influence the length of time we spend. I think the father will be happy either way.

We really enjoyed both back in January 2013 (even though it poured rain at Herculaneum, which cut our visit short), and as Lesley noted, Pompeii is larger so could involve lots more walking. The audio guide was helpful at Herculaneum (although an 11-year old may not want to use one?) for learning such things as that the laundry at Herculaneum used urine to whiten togas!

Good post by Michael. To add:

Hurculaneum is farther from the train, if still less walking than Pompeii, and has only dry-food and drink, vending machines inside the site. Pompeii has a full tourist-hot-food canteen inside. (Neither site allows re-admission the same day.) Herc is a longer ride from Sorrento. Although you don't raise the issue, serious art-tourists might want to know which Villas are closed-for-work at each site. You are correct that either site is enough for the casual tourist.

I wonder though if cocktail-party and water-cooler chatter is easier with the answer, "Pompeii".

Herculaneum was a surprise, I would think that if only going to one I'd take my grandchildren there rather than Pompeii. Herculaneum is compact and would be more real . Time wise a couple hours.

I have also really enjoyed the relatively-intact buildings and much smaller crowds at Herculaneum, so I think it's a good starting place.

If you go to Herculaneum, note that there are only vending machines inside the site, as well as perfectly good toilets. If you need lunch, while walking back uphill to the Circumvesuviana, consider Spaghetteria/Ristorante-Pizzeria-Caffetteria on your right at Via IV Novembre, 11. That is the main street you are walking all the way to the train. Note: You cannot re-enter either Pompeii or Herculaneum after you exit the site. So plan strategically for lunch.

It's not fine food, and very modest. But we (May, 2014) got made-to-order pizza from a wood-fired oven in about five minutes. It is much better than it looks, and inexpensive. There is no fancier-looking place on the walk, BTW!