My vote would be for content, or other sites (for diversification).
Perhaps this is market dependent - but I'd be very careful with that strategy based on my own experience:
I get great satisfaction from watching competitor's million pound TV ad campaigns in the evening, and then noting their web site traffic hasn't budged an inch the next day.
The offline-online gap is HUGE. Unless you've got the budget to make yourself a household name (tens or hundreds of millions) - then I think offline advertising is often a waste of money.
Your experience (in a different niche) may vary.