She was by no means from Hell but can I nominate my mum as putting me through Purgatory in Barcelona? 
We stayed here. I recommend it. DH and I have stayed lots of times. Small pool on the roof, which is unusual. Most importantly, it's in a very safe area of the city. Some might call it bland, so it wouldn't suit everyone, but safety is a real bonus with an elderly lady. My mum wasn't that timid but she liked to feel safe. Good for shopping too.
I went away just with her for three nights. We were upgraded to a junior suite - this is important, not just because my mum was so impressed by the receptionist's major sucking up (that's a Pretty Woman reference btw; I don't expect people to suck up to me, and neither did my mum, but we loved it) - but because she behaved like an excited six year old when she saw the rooms.
She sat in the armchairs, the desk chair, the chaise longue, the sofa bed before checking out the bathroom for toiletries and plundering the complimentary fruit basket.
We ordered a cooked breakfast on room service. She loved ticking off the options. She also loved and saved the rose that came with it.
Less endearing was that she wanted to keep the things we couldn't eat. Pastries and jam fine. Sausages and bacon, not so much.
She stashed them in the wardrobe. I fretted about it on a trip to La Pedrera which is just up the road. Again, I recommend it. My mum would too. She was a bit younger but the things they have in this beautiful state-of-the-art 1910-ish apartment filtered down to poorer people in the '20s or '30s.
She scoffed about my wimpishness. I envisioned ants and cockroaches and being drummed from the hotel.
We went back. The room smelled like a short order cafe. She ceremonially dumped everything in a bin outside with a look that said: 'You are such a weed and a wastrel.'
What can I say? I am. But oh God, at the time.
BTW what I said about it being great that we were upgraded was that we were sharing a bed - fine, I loved my mum and that was that was completely natural to me.
However, she snored like a warthog and insisted on being up at 7am to see the sights.
At 2am I crept out of bed, dragged a blanket with me, closed the doors and bunked up on the sofa bed. I was too tired to pull it out.
I do miss her though.