a star destroyer? You can just get the official model (if you have the cash, that is), which from what I have heard is gigantic, probably as big as that model.
Anyway, that other thing is a cool MOC, although it doesn't look like much more than a display model. But if you really want big things, take a look at this one:
http://www.legotrucks.com/dennisbosman/html/intro/cmno04.html(he says this thing is 13.7 feet high when fully extended)
But anyway, I don't think that good models are necessarily big, nor the converse. It's better to pack more functionality into a smaller space if possible.
What themes are you into? I mostly build space stuff on minifig scale along with just about anything technic, and I am also into some town, aquazone and model team things. Scored an unopened 6987 message intercept base recently, but I paid through the nose for it even though it was much cheaper than the usual prices for that set.
I need to try building some FS fighters sometime; the shivan color scheme would look excellent, and those destroyer droids included in a few of the star wars sets actually look a bit like shivans.