Need advice on Greek islands
 

We are planning to go to Greek islands in begging of October Santorini first for 4 nights then Mykonos then fly back to Athens for flight to USA 5 nights in Mykonos is this good or should we do another trip?

A little confused..4 N Santorini, 5 N Mykonos? I would do 2-3 each and the remainder on Paros or Naxos to get you away from those other touristic islands.

October is a good time for Santorini and Mykonos, as it is quieter than the busy high season. Do you intend to spend some time in Athens, or just go back for the flight home?

i agree with HappyTrvlr about Paros or Naxos, but caution you against trying to visit too many islands in a short trip. The season ends earlier on Paros and Naxos, and it will be very quiet in October, with shops and restaurants starting to close for the winter.

We are not spending time in Athens and want to relax not run around to too many islands

Then, I would substitute Naxos or Paros for either Santorini or Mykonos. We prefered Mykonos to Santorini.

Repeat visitors like HappyTrvlr and myself often prefer Naxos and Paros, but they are too quiet for me after mid-September, and I am in my 70s. If all you want to do is relax and aren't bothered about missing the world-class sights of Santorini (caldera villages and Akrotiri), and Mykonos (Delos and Mykonos Town), then Naxos and Paros would be good choices.

Another factor to consider, since you are not spending time in Athens at the end of the trip, is reliability of connections to Athens Airport. Both Mykonos and Santorini have airports served by regional jets, while Naxos and Paros have smaller airports served by small turboprops.

By October the new Paros Airport should be open, and served by 78 pax Q400 turboprops, while Naxos will continue to have a couple of flights per day on 30+ Dash 8-100 turboprops. According to the Aegean Airlines website there appear to be no flights from Naxos on Saturdays in October. After the new Paros Airport opens in July there will likely be timetable changes, so I wouldn't rely completely on what is currently displayed.

In summary, my recommendation would be to go to Mykonos and Santorini on this trip. With any luck you will become hooked on the Greek Islands, and come back to experience wonderful Naxos and Paros.

Thanks I've been to both on a cruise and wanted to spend time on each this time

If you like to party, choose Mykonos. If you want one of the most magical places, go to Oia on Santorini.