I'd suggest the IP for the cheapest option on the strip and yet a Harrahs/Caesars property.
I'd also suggest the Gold Coast off strip for a nice clean reasonable rate room that does have a shuttle running to the strip itself.But if your family may have access problems boarding,standing in line waiting for the shuttle etc.Then definetly take a look at the IP..Too bad it has to be only a 2 day trip,but an on-strip stay does free up a lot of time stuck in traffic etc.It is nice to walk outside hotel and be right there with the car safely tucked away in the garage.Hope they have a good time!