I have been pondering the architectural qualities of Seaton Delaval since visiting yesterday: it is partly owing to the amount of exterior activity in relation to the relatively small building behind. On the garden façade, there is an immense portico contained between the two corner turrets, so that it is nearly all portico, which is presumably why John Dobson proposed flanking wings in the early nineteenth century to reduce the sense of compression in its façade:-

Also, Vanbrugh uses big blocks of stone in a very abstract way to give architectural emphasis:-