I've kind of had a similar experience LlamaMamma. After messing around with WA and Ambitions for many months, I went back and started playing an old Legacy family in SV that I started shortly after the base game came out. They were on gen 6, and only were worth 200k simolians, I think that about sums it up! It's WAY easier to gain money with the two expansions! I have other families that have that much money or more after just 1 generation. And with that old Legacy, I had completed a ton of LTW's, one for each sim in the household, many of which were "reach the top of _______ career".
One of my newer Legacies post-WA had over 3 million simolians, and they were only on gen 5.
Anyway, as for Twinbrook I think Charmaine Mann is a good catch, and I'm also having fun with Amy Bull in my Dynasty. For Legacies, I really just go with whoever they happen to meet and like first, and then I just work with whatever I get. I'm not very strategic about it.