Hi Nero
We stayed at the Alianthos Beach Hotel every year from 1996 to 2004 (didn't make it to Plakias last year!). and we like it!
The first two years we travelled with First Choice and the rooms we had were at the back of the hotel looking up the alley towards what was then the Crazy Dolphin. Subsequent years we travelled independently, booking direct with the Alianthos, and from then on we got a room at the front overlooking the beach. We found all the staff to be very helpful and very friendly, in fact going back year after year, you get to be treated more like old friends. The rooms fairly standard and are cleaned every day, towels are changed every day and bed linen every couple of days. The rooms have a fridge and TV (for those who can't live without) but not much in the way of English speaking channels.
Hope this helps.
Jan