Spent night before last in Rennaissance Wien, and last night in the IRS. Family of three, both times in Club room (upgraded at IRS). Both have great locations, though IRS is of course closer to Ringstraße.

We had a corner room in both hotels, the Renaissance Wien had a sofa bed which meant we didn't have to pay for a rollaway bed. The bathroom is annoying because it's not a full wall between the bathroom so the light seeps into the room. Breakfast was okay with basic fare of waffles, bacon, omelette, etc, but they only offered complementary for 2 people.

The IRS room was bigger, but the coach didn't have a bed in it. Bathroom included a bath while the Ren Wien didnt. The lounge is good, breakfast was standard fare again. Dinner on Sunday night was only cold food, other than a good warm soup. Today it was warm samosas, rice, and chicken. We tried to check in at noon, but the room wasn't ready. We were given cards to get into the lounge and told to come back at 3. Came back, room still wasn't ready, but they had another room and moved us there. I asked for a late checkout today through the app, but was only given until 2 rather than the 4pm I wanted because the hotel was completely full today. The main building can get really loud, but the club building across the way is very nice.

Bottom line I'd stay at IRS over Ren Wien unless there is a large difference in price.

Also met a fellow Flyertalker in the lounge in IRS!