I have a child, and am wondering what program to accrue their (and future children's) miles to for purposes of redemption. I don't anticipate status in the near future for myself. I have ~785k lifetime flight miles on United so I'm inclined to keep crediting my UA flights there (in... oh, 30 years... I may have MM!)

(1) What is your home airport? (SFO, LAX, MCO, etc.)
New York - any.
(2) What types of fares do you usually buy ? (C, F, Y, etc.)
Economy as a family.
(3) How many miles do you usually fly each year? (<25K, 25k-50k, >50k)
~15- 20k as a family
(4) Do you have any kind of status at present? What is it? (UA Silver, M&M Senator etc)
None for my child.
(5) What is most important to you in a FFP? (Frequent upgrades on travel, priority services when flying the airline, good award redemption rates, free lounge access, etc.)
Redemptions: I want to be able to use these points for flights or upgrades (I don't care what as long as I get reasonable value per common valuations - say > 1.3c/mi). Ideally I could transfer credit card points (either now or when they are 13, directly or via pooling) to top up and redeem.
(6) Which routes do you fly most often (US Domestic, Transpacific etc)
Expect ~4 US/NA domestic + 1 trans-atlantic/pacific each year.
(7) Preferred Airlines
No strong preferences. Whatever is cheapest for the enough legroom (E+ or a different airline)
(8) Do you travel for work or pleasure? (Can you chooose your airlines, class of service?)
Pleasure - completely free choice here.

Thanks for the help!