Just visited the Club at LAS in the D concourse yesterday morning. Positives were the friendly staff and selection of beverages. The averages were the food selection and the views ( a limited view of the Tarmac and an extensive view of the Tram escalators). The negatives were the size of the two rooms, the lack of facilities and the crowded and small furniture.
At 6:00am Wednesday the place is empty. On Sunday at 1pm all of the seats appeared to be taken so I did not even try to enter.
As a Priority Pass holder through the Ascend Card I went to judge for myself. I do not think it measures up to the UC, but is an alternative. Neither matches the Centurion Club.