We've disabled the big garage door so it can't be used as a garage as such any more - at least not without a grat deal of unscrewing and unbolting from the inside.
There are a couple of windows in the garage which have iron bars across them - we did have an attempted brak in through one of the windows but the theif was un able to gain access. Which is a good job, because at present the bikes aren't secured too well. They're cable locked to the roof ladders which are hanging on the wall! - the theory being that it would be quite arkward and noisy to remove them.
We have a cunning plan to insall some proper secure wall/floor bolts, but its on a long list of jobs still to do.
All that said, my main (most expensive) bike is kept in the porch as its in and out several times a day usually.