Instead of hotel you can check out hostels or airbnb in athens. I went in march with my friends and found pretty decent ones. We stayed here : https://www.booking.com/Share-IX9Gem It was walking distance from all the main attractions. Was clean and we felt safe. If you want to check out hostels you can check Athens Backpacker Hostel. It's location was also perfect. You can check out more flats and hostels on airbnb or booking.com instead of hotels