Athens - flat rate taxi fare airport to city center
 

I understand there is a flat rate of 35Euro from airport to city center during daytime hours - it goes up for nights. Can anyone confirm this (used it)?). are there fees in addition? I will be going from the airport to grand bretagne hotel.

€35 between 6am and midnight, 50€ after. If the driver handles your bags in and out of the trunk of the car there might be an additional charge.

If you are arriving during the daytime hours the Blue Line Airport Metro is a lot cheaper and faster. It stops at the Syntagma Square Metro Station, which is across the street from the Grand Bretagne. A one-way Metro ticket for 2 people is €14.

brotherlee, it is the obligation of the taxidriver to handle the bags in and out of the trunk.. and there is no charge for that of course...

I don't take taxis so I can't speak from experience, but I have read many times of extra charges being levied from handling baggage. Perhaps it was one of the scams the dishonest drivers would pull on unsuspecting tourists?

If someone got charged for that, then it was a scam...
This one of the reasons why the Ministry of Transportation invented the flat rate.
In addition to that, i would always write down the plate number of the taxi, and would also ask for a receipt.

is it 35 euros per person as my sister and I will traveling?

it is 35 euros per vehicle...
just keep in mind that a taxi has space only for 3 persons with luggage... the forth will have to take a second taxi.

Also the flat rate is only valid for hotels inside the inner city ring..

Yes, the flat rate includes EVERYTHING, tolls, bags, taxes etc. The only time any addition is acceptable & charged is if it's a radio taxi, ie: you want to go TO the airport & the hotel called a cab for you. This should be between 3-5 euros, usually 5 for an airport journey.
The airport taxis have yellow cards taped to the dashboard in the front of the cab, there was always one anyway, now there is a second one with these details on there (at, or close to the bottom of it)in English & Greek.
As someone who speaks some greek (enough to get in, give directions, & make it clear i knew about the flat rate) there was one driver still tried a scam by saying I had to pay the toll. I argued with him as I knew I was right & had been prepared for this, so had the exact money & didn't hand it over until he had got all the luggage out at our destination.
The area map of central Athens where this flat rate applies is here,
http://www.aia.gr/UserFiles/File/map..._daktilios.pdf
There are a few hotels that are a matter of yards outside of it, mainly in the Syngrou area.
Anyone enquiring about this on here, please include the hotel &/or the address of your destination for clarification.

BTW, the flat rate of 35 (or 50) is decided by the time of ARRIVAL at your destination, not the time you get in the taxi. So if you have an early flight, get a taxi at 4.30am, but don't get to the airport until 5.15, you pay the day rate.
http://www.aia.gr/pages.asp?pageid=988&langid=2

Thanks to all for the prompt and useful replies! Don't speak greek but I think I can make clear thru the dispatcher that I understand the terms of the flat rate...or point to the sign on the dash. I will make sure to have exact change as well altho I suspect the hotel bellman/concierge should be able to help me cope with issues if there are any.