We are going to Greece and don't know if it is better to go last week of August first week of September or first two weeks of September over labor day. I know it is less crowded once the kids goback to school but do things close down? What is the weather like? I appreciate any comments and thanks -

September weather is excellent. The crowds have thinned down, the water is warm and the evenings balmy. Between those two choices go with the first two weeks of September.

While I have to admit I have not visited Greece in August (Our time is late May early June) I have been following the Greek forums for years and the consensus opinion is late August is still quite hot and is still high season. The Greek school children are back in school by the last week of August so it does tend to slow down a bit. Early September will be quite warm, there will still be lots of tourists around but the summer hoards of people will be gone. Everything will still be open. I suspect it will be very similar to our June time except the water will be much warmer.
Have fun planning

We have been to Greece a few times and were there in August this year. It was extremely hot and humid and we come from a hot climate so should be used to it. I would say go in September when it will still be warm but a bit more pleasant.

Kay

You asked about Greece, but didn't specify whether you meant the mainland or islands.

The last week of August is one of my favorite times to be on the Greek Islands, but I enjoy it when it is busy. High season on the islands is considered to be through Aug 20th, and after that prices drop and crowds begin to thin. The change is noticeable almost day to day, and by the second week of September smaller islands will be very quiet. The more touristy islands, e.g. Mykonos and Santorini, stay busy well into September. High season doesn't really apply on the mainland, except in some of the coastal resorts.

All things considered, I agree the first two weeks of September will probably be the best choice for you. A few hotels and restaurants close after the first week, but they are the less popular ones anyway. Prices in hotels are lower, and shops begin their end of summer sales. ;-) Ferry companies continue their full summer service until about Sep 12th or 13th.

We're recently back from ten days spent in Athens, Santorini and Nafplion (thanks to all you Fodorites who made some great recommendations...), from 9th September to the 19th. The weather was beautiful, everything was open, all services seemed to be running, and nothing was especially crowded. I've never been there in August but I'd recommend September very highly.

Thanks to all of you, you have truly helped. My trip will be better because of your help.