I recently stayed for five nights at the Marriott Ledra in Athens. It is in the best style of Marriott hotels, with new bedding, spacious bedrooms and bathrooms, flat screen TVs, dual voltage plugs for computers, etc.
The Executive Lounge is one of the best I've seen anywhere. It is open almost all day seven days a week. There is breakfast starting at 6 (weekends 7), cocktail hour with hors d'oeuvres from 5-7, dessert hour with cocktails from 7-9 and unlimited access for soft drinks, snacks and access to computers and printers. The staff is wonderful, especially Nikos, who makes every guest feel special.
Their concierge, Alex Stefanos, is also wonderful. Since it was my first trip to Athens, I decided to do tours. The hotel uses Key Tours and I had amazing tours of Delphi, Mycenae/Epidaurus, 3 Greek islands in one long day, and Cape Sounion. The tour guides really know their stuff.
My points were credited the day after the stay -- something I find rare with most Marriotts in Europe, where it can often be a hassle to get points posted.
A word of warning for solo female travelers. Unless you speak Greek, don't hail a cab on the street (one from the hotel is fine). I overheard one other female guest relating to friends in the Executive Lounge exactly what had happened to me the same day. I hailed a cab, told the driver I was going to the Marriott only to be told there was no Marriott, that I meant the Meridien. Then he went the wrong direction (I had come to know Syngrou St a little by then) and when I pointed it out he argued with me. Then he stopped in front of a Greek bank and said that was my hotel. I got out my card key and showed him the address and he said, no, we were there. Finally I grudgingly paid him 3 euros and told him I was getting out right there. I managed to get my bearings and found the Marriott a few blocks down on the other side of Syngrou. The other woman in the lounge with the same experience said the driver tried to keep her hotel key card and had to grab it back from him. This has nothing to do with the Marriott -- any cabs that pick you up there are following strict rules.
My one and only issue was the minibar. Check your charges! I rarely use it, but did the first day because I didn't realize what was available in the Executive Lounge. The items I took were not replaced and I was charged twice. The desk clerk even thought it looked odd and asked me and corrected it immediately. Internet is pricey (19.95 euros a day), but that is true in most places in Europe and you can use their free computers in the Executive Lounge instead.
All in all, Greece (esp outside of Athens, but doing so through day trips) was amazing and the Ledra was fantastic!