Have seven days to visit Mykonos, Paros, Naxos. How long to visit each?

You actually need a minimum of 3 full days to enjoy an island, so cut one of these three from your proposed itinerary. Unless high-end shopping and expensive bar hopping are what you're after I suggest you eliminate Mykonos. If it matters, you can still see Delos on an excursion boat from Naxos and Paros.

Thank you for the information

I say 3 nights (visit Delos from here) Mykonos, skip Paros, santorini 2nights, naxos 2nights.

Definitely visit Delos from Mykonos. Very easy to get to via local boat(s) and should not be missed. Will take one half to three quarters of a day, but if one is really into Greek history one could spend all day.

Seven days in Naxos! Naxos is similar to Paros (each has its partisans), Mykonos is fancier and less authentic.

Mykonos is great for the nightlife. Lots of bars and clubs, if that's your thing. Very touristy.

Everyone goes to Santorini because they want to go to Oia, the village where they take those photos of whitewashed houses with blue-domed roofs. It is beautiful but also very touristy.

Naxos and Paros are pretty similar, small and sleepy and relaxing. I LOVED Naxos. It's my favorite island. There is an unfinished temple just a short walk from the waterfront of the main town. All that stands are the foundations and the doorway. It's gorgeous.

I agree with the others that you should go to Delos. It's a short boat ride from Mykonos and if you're a history or archaeology buff (like me), you will LOVE it. It is amazing.

I think 2 nights each is long enough for Mykonos and Santorini. 1 night each for Naxos and Paros. Or skip Paros and spend 2 nights in Naxos.

After spending 8 days driving around Peloponnese March 24 thru April 2 we plan to catch a ferry to Mykinos then Santorini. Just wife and I, 2-3 days exploring each island. I like the idea of visiting Dilos and Naxos. Thinking about visiting Naxos on way to Santorini, is this a good idea or should we plan on spending night there. Interested in others experience and lodging recommendations.

Since Santorini & Mykonos are two of the most popular, heavily touristed and expensive of the Greek Islands I would drop Mykonos and spend more time on Naxos, one of Greece's most beautiful islands with something for everyone.

You can do the Delos/Mykonos day cruise and experience Delos, one of ancient Greece's most important sites with fantastic remains that rival Pompeii in Italy without the crowds.

Mykonos while visually stunning is expensive, crowded and you'll see large cruise ships lurking off-shore spewing out hundreds if not thousands of tourists at a time, same goes for Santorini.

You can get to Delos/Mykonos from Naxos but with a longer ride, experience Mykonos without the expensive costs of staying there and return to Naxos, an island will give you a wonderful experience of why people go to a Greek Island, tradition, lower costs, archeological/historic sites, beaches, mountains, centuries-old Byzantine Churches, great tavernas and food and people more concerned with showing you Greece rather than making a buck off of tourists!