I've stayed at the Halyard a few times now. I can't say whether it's as posh as the hotels you refer to in Lisbon and Porto, but it is nicely fitted out to a high standard. The only cons for me are the rooms are a little small and the bathroom doors are sliding, which always feels like it gives less privacy. Not an issue if you're in separate rooms. If you're with your mum you'd probably want separate rooms if you do go with the Halyard.

The CP has more amenities (pool, etc) and the staff in the lounge at the CP are absolutely brilliant. The food in the lounge, and the lounge itself, is rather meh. But they are generous with the drinks, and the wine is nice enough to my uncultured palate. The rooms are nice and clean and comfortable and well maintained but they're very 90s.

Probably comes down to taste. I now prefer the Halyard, Mrs Troll still prefers the CP, so as a compromise we do still normally stay at the CP. And there's no complaints from me about it. The staff there really are great.

I've not stayed in the Indigo. I have stayed in the Holiday Inn at Lime Street and you couldn't pay me to stay there again.

As for location, it depends what you mean by "getting around". It is a walk to the CP from the main bit of the city centre and the walk- scenic as it is next to the Three Graces- does get rather boring rather quickly, especially if it is wet. There isn't much around the CP in terms of bars, restaurants, etc. The Halyard is much more central, it's about a five minute walk to Central station and about 10 to Lime Street. But the Ropewalks area it is in is 'lively'.