100 X 100 should be just about a perfect height for most rooms, unless you want higher ceilings. What format and program are you using? Scales on some formats can do really strange things upon export. In GG, 100 units in DirectX format = 100 inches.
EDIT
fyi, .fbx can often be larger, .obl can often be smaller, either by factors of 10!)
Desktop: i7 4770@3.4Ghz, 12GB RAM, Win 10/64, GeForce GTX 1080, 1TB SSD, 1TB HDD; Laptop: i7 4800MQ@2.7Ghz, 16GB RAM, Win 10/64, GeForce GTX870M , 1TB SSD.