I was there three years ago with most probably the same company. The Liberty is a lovely hotel well positioned in Riva Del Garda, close to everything. Unfortunately it is the luck of the draw as to the standard of room that you are given. Some people in our group were complaining about their room. In our case we got a good room so we cannot complain. The food is basic, nothing really Italian. It looked as if it all came from a packet. Even though your parents have paid as individuals for this holiday they will be treated as part of a group and herded as part of a group. Yes, they are expected to sit at the same table every evening but worse still they are expected to share the table with another couple within the group. My suggestion is to say to the head waiter that they are celebrating a wedding anniversary and would like a table alone. We did this after the first night when our overpowering table companion kept taking chewed food out of her mouth and leave it on the side of her plate. No way were we going to spend seven days suffering with that carry on. We had to put up a bit of a fight though to get our way.
There is a lovely swimming pool and wellness centre in the basement and an outdoor pool as well. The various day trips available around the lake are very enjoyable as is the day trip to Venice although a bit of a journey in the coach. Verona wasn't great. There are great walks along the lakeside, especially the one to Torbole. Hopping on and off the water buses is great, bring a sweater, especially to Malcesine and Limone. Riva gets cool in the late afternoon and can have downpours of rain so an umbrella is useful.