We do a lot of work in Vegas, often with a focus on conventions. When we're working at the Sands Convention Center, the Grand Lux is our standard choice for meals. The food quality is always good, the meals are a good size, the prices are very reasonable and the service is typically fair. The menu is HUGE so there's always something you'll find to eat and you can eat 2 meals a day at this restaurant for a week without having to get the same thing twice.
We find this to be an easy choice when in Vegas and eat there several times during every trip. We've had many large parties there (never with a reservation) and many business meetings as well as quick lunches for two, all with equal success. Their lunch pizza and salad are YUMMY!