Hi there - I am heading to Iguazu in September and I am staying at The Iguazu Grand Hotel (Our little one-off indulgence for our trip)
Their sister hotel is the Panoramic and from the looks of things, it is lovely.
Unfortunatley I have already prebooked and paid to stay at the Hotel Esturion for our last night in Iguazu - (The Grand was too much out of our price range to try and stay 3 nights.)
Looking at reviews on here, the Esturion doesn't sound too well liked, so if i had the chance to change our reservation I would definately be looking at the Panormanic.
The people I have been dealing with for our stay at the Iguazu Grand are sooooo helpful - they even emailed me a full sheet of things to do and things to bring to Iguazu.
If you are looking for friendliness I would definatley recommend the Panoramic as the people I have been dealing with also own and run the Panoramic and I am sure they would offer the same friendliness!
I haven't stayed in Iguazu yet but if you look at the reviews on Trip Advisor they will give you a good indication of what people think.
Sorry I couldn't help more,
Hope you enjoy your trip!!!