So I really like triconsonontal roots, but I haven't been able to find even a little bit of information on how they age and spawn daughters. Since part of my idea here is to have a parent language and its descendants, 3cs are right out, alas. Unless I just punt to "the sounds may change but the patterns stay the same," which seems like a cop-out.
Ergativity is fun. Also polysynthesis, but I think I'm going to stick with one or the other. And since I understand ergativity much better than I do polysynthesis, ergativity wins. Maybe one of the daughters can transition to nom-acc and then develop polysynthesis. It hasn't happened anywhere in the real world that I know of, but that's OK. This implies a case system, and explain why I do this to myself again? I'd really love to be able, someday, to actually speak one of my conlangs.
Head-initial or head-final? I rather like head-initial, only really, like Welsh, instead of half-assed like English. OK, verbs go at the beginning. This implies modifiers following their heads, like in French, and prepositions.
I'm sure I'll come up with more later.