Using the Poisson-Boltzmann-Flory approach and a cell model, we examine the properties of dendritic polyelectrolytes and counterions in a broad range of molecular weights under variation of dendrimer generation and spacer length. The theory predicts that for the assumed cell size the lower generation dendrimers exist in the polyelectrolyte regime characterized by low and nearly uniform counterion densities. When the dendrimer generation is increased beyond G7, a crossover to the osmotic regime occurs where pronounced condensation of counterions onto the dendrimers takes place. In both regimes the molecules are swollen as related to their neutral state. For a given spacer length the expansion factor changes nonmonotonously with dendrimer generation and is maximal at the crossover. For fixed generation in the polyelectrolyte regime, it is the greatest for shorter spacer chains. The dendrimer effective charge grows monotonously with increasing generation number and, for a given generation in the osmotic regime, is subtly affected by spacer length. The theory also reveals an effect of both parameters of the dendritic architecture on the mean electrostatic potential, the electric field, and the zeta potential.