Flying long haul in First is a great way to use Avios. It's the only way a lot of people get to experience flying first class and I'd very much recommend it.

You may have seen it already, but this thread has info on how to earn and boost Avios - pertinent as it wouldn't take many more for you to fund a flight to many long-haul destinations. Cape Town, for instance, is 150k Avios.