It depends on the whens and wheres I am in a game run. I always keep my heir unlanded, but the spares get baronies, counties, or duchies depending on how large an area I control

I land my childe depending on my military strength, if im a single duchy I won't land them but if im a Kingdom+ and am expanding I'll land my children occasionally to eventually make Kings on their own

But if you're after renown just land a member of your Clan and not family (Lasombra ruler landing a Lasombra vampire will give renown to the whole clan) the only exception is if you're playing Cantiff

When im starting out I just use children as knight fodder (along with ghouls) and i tend to give land out to vampires to make the best knights i can find