Hi EddieB. Jen has serious walking problems, and would find the hill a trial if she had to go up and down many times. Mathraki is a great place to stay though. Own lovely pool, wonderful hosts, good reports from everyone on here so far. It isn't that far up the hill, and like Ang says, there is a back street way up there past Efithia on the sea front.
But I get the feeling you might do better in the sea front accommodation - hotel style in Marina or Horizon, or apartments in Mirage, Marinaki, or any of those set just behind, like Brouklis, Rainbow, Irene's or Bardis Sun.
Happy to help - send me a PM if you want any information I can give you.
Phil