For me Tripadvisor is the best choice for hotel and attraction reviews. I have benefitted many times from the reviews and also through the TA forums.
I actually use the TA forums quite a bit – and there are always a few contributors who are specialists for the specific forum and their advice/feedback/reviews hardly go wrong.
I also go through the hotel reviews at booking.com – but dont find them much of an help. Mostly it is written in a hurry or very short with not much of helpful tips.