I've been to Grand Lux Cafe twice now and both visits have left me happy. I'm a fan of anywhere that has breakfast/brunch options all day, and Grand Lux offers just that and more.
On my last visit to Vegas, we came here for a late brunch and were seated right away, despite how busy the place was. They have a pretty extensive weekend brunch menu and lunch menu so there's tons of options to choose from. I ended up getting the eggs any style and your choice of bacon, ham, or sausage links with toast and hash browns. This was more than enough food and my tummy was very happy.
Service was quick and efficient. We were helped out by a couple different servers and they both always made sure we had enough water, coffee, and were both more than happy to give suggestions/recommendations.
If you find yourself roaming around The Venetian looking for a solid breakfast/brunch spot, Grand Lux Cafe is perfect. They are also open late night, so it's definitely an option when you're coming home from the clubs.