A conventional rooftop design, assuming you have reasonable line of sight to the transmitter and there's not too much attenuation from the structure of the building.
But can't you persuade the folks to let you have an exterior one?
Sadly not, but it's not an aesthetics thing, my dad claims that they increase the chance of your house getting struck by lightning......
But because of the inside problem, what is best? I can get a pretty big beast up there and we have some serious signal strength meter things and what not that we got from my uncle...our TV reception on digital and analogue is superb though - our old 60" Grundig CRT would show up the faults in no time! lol!