Gets the job done
Four nights solo as a 39 year old bachelor in Athens in late November 2018, so here's my deal. I am Hilton Gold as a benefit of my credit card, so my experience may differ from yours.
Arrived in the evening to a very crowded lobby as a conference/meeting was ongoing on a couple of ground levels. As Hilton Gold I was sent up to the 11th floor for Executive Level check in. Lots of quick elevators were available to take me to the friendly lounge. From I believe 6-8 nightly they offer light snacks and some local beer, wine, and bottled water. The lounge is open day and night as a place for a nice view of the Acropolis and to get some space and have a coffee or unwind. Check-in was quick and friendly, was then to my room to drop my things and came back with my laptop for a drink and to plan my evening a bit.
Room was King Bed, 10th Floor, nice spacious bathroom, plenty of closet space, fully stocked mini bar, functioning safe. Big balcony with a view of Acropolis that I had selected specifically with a table and two chairs to take it all in. I'm not a smoker, but smokers will appreciate this.
Gym and Spa - I checked them out but got enough exercise walking to not make the time.
Breakfast - Continental in the Exec Lounge or a bigger spread downstairs. I don't really take breakfast and Greeks often don't either, so I can't comment.
Internet - Good enough.
Mini-Bar - Well stocked, but if you use anything you best ask them to restock it as they never did for me. It has the auto-billing feature, so keep that in mind if you want to put groceries in the fridge. Hilton usually will bring you a separate mini-fridge on request which I recommend here.
Room Service - Had a late night pizza one evening that was lovely. Friendly service.
Location - 15-20 minutes walk to many attractions. People will tell you Uber is gone in Athens, but it isn't, it's just now booking you to local yellow taxis who are very friendly and effective. Keep in mind that traffic might take them longer to get to your so factor this in when planning your evenings.