I would also recommend walking from the Lake Mead National Recreation Area Visitor Center (before the fee entry gate) along the old railroad bed toward the dam. One cannot walk all the way, so it is a roundtrip, but a great overview in the cooler hours of the day.

It is suitable for young children and folks in wheelchairs.

As for touring inside the dam, my wife & I did the "complete" (more expensive) tour in May 2013 and greatly enjoyed it. My father was a civil engineer and we had driven over the dam in 1972 on our way to the Grand Canyon. Mrs. Lifer & I moved to Las Vegas in 2018 for 32 months with our young adult sons.