ample, capacious, commodious, spacious

cavernous, voluminousbroad, widebig, biggish, bulky, considerable, generous, goodly, grand, great, handsome, hefty, hulking, large, largish, outsize(also outsized), overscale(or overscaled), oversize(or oversized), sizable(or sizeable), substantial, tidyBrobdingnagian, Bunyanesque, colossal, elephantine, enormous, gargantuan, gigantic, herculean, heroic(also heroical), Himalayan, huge, humongous(also humungous), immense, jumbo, king-size(or king-sized), leviathan, mammoth, massive, monolithic, monstrous, monumental, mountainous, pharaonic, prodigious, staggering, stupendous, super, titanic, tremendousexpansive, extended, extensive, vastboundless, limitless, unbounded