Although urban agglomerations are vital sites for national economic development, comprehensive multidimensional investigations of their performance are lacking. Accordingly, we examined land use efficiency from multiple perspectives in two of the earliest developed and most advanced urban agglomerations in China, the Beijing–Tianjin–Hebei (BTH) region and the Yangtze River Delta (YRD), using different metrics, including trans-regional drivers of the spatial allocation of construction land. We found that: (1) The land use efficiency of urban agglomerations was context dependent. Whereas it was higher in the Beijing–Tianjin–Hebei region for population density per unit area of construction land than in the Yangtze River Delta region, the opposite was true for gross domestic production. Thus, a single aspect did not fully reflect the land use efficiency of urban agglomerations. (2) The land use efficiency of the two urban agglomerations was also scale dependent, and in the Yangtze River Delta region, the use of multiple metrics induced variations between aggregate and local measures. Median values for the land use efficiency of cities within an urban agglomeration were the most representative for comparative purposes. (3) The drivers of the spatial allocation of construction land were trans-regional. At the regional scale, most topographical factors were restrictive. Major regional transport networks significantly influenced the occurrence of construction land near them. Dominant cities and urban areas within each city exerted remote effects on non-dominant cities and rural areas. In principle, the median value can be considered a promising metric for assessing an urban agglomeration’s performance. We suggest that stringent management of land use in areas located along regional rail tracks/roadways may promote sustainable land use.