We stayed at Cape Sounio for 10 days in August of this year. It is a nice hotel and on the whole, the staff were friendly and helpful.
We had a family bungalow quite close to the main hotel. The rooms were clean and comfortable but small. The double bed in one room took up the whole room and had to be accessed from the foot of the bed. The bed in the other room was pushed against a wall so the person sleeping on the wall side had to climb to the end of the bed to get in and out.
The swimming pool is in a nice area close to the outdoor restaurant, which makes it easy to have lunch, snacks or drinks. It is filled with salt water though, so this might be an issue for children when water gets in to their mouths as it invariably does.
There is NO shade by the pool apart from one tree in the far corner. There are parasols, but you are not allowed to have them up if it is windy. I found this ridiculous as it meant that you couldn't spend long outside, especially with children as there was no way of spending some time in the shade. I certainly didn't appreciate being reprimanded by the pool staff for opening a parasol and then to have them come and close it!
The beach is through a tunnel under the road and is small but pretty. The water is shallow a long way out and it is safe for children. The sun loungers are pretty close together but overall it is a good beach with a lovely view.
If you are travelling with children you should note that the "Kids Club" is in effect, a large tent at the back of the hotel. The temperature inside is madly hot and the toilets have definitely seen better days. The staff there are very good though and as our daughter only wanted to take part in one or two of the (mainly outdoor) activities none of this was a problem for us. However, if you are thinking of leaving a child there for a whole morning or afternoon I would think twice as the facilities just aren't up to scratch.
This hotel seems to attract a lot of business travellers, which given that it is only an hour outside Athens is not really surprising. However, it does give the hotel a slightly different feel from a pure holiday hotel.
Our only issue with the hotel was in relation to the the service on the terrace. We would have liked to have had a drink before dinner each night, but the service was just agonisingly slow here. We waited at least half an hour every night before we were served a drink, which I found vaguely annoying given that the hotel was nowhere near full. The hotel must be losing money here as people just didn't bother waiting around and went straight in to dinner instead. The spa is very nice and there are lovely views from the various terraces at the hotel.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC