I can't see Rachel getting into the military. You have to be disciplined, and follow orders without question. Rachel could just barely follow orders from Jake, who was someone she respected probably more than anyone else. On the other hand, of course, the military might have seen her as an experienced veteran and cut her some slack because of that. Still, too much insubordination, and she would have been kicked out. Police work might have been more forgiving, but too tame.
However, the fact that she has a whole support network of people who care about her is something I hadn't really considered, and a very good point. Yeah, that would definitely help to keep her from committing suicide, at least.
Still, most of them didn't really understand the depth of what she went through in the war, so I'm not sure to what extent they'd be able to help her to get past it. The war was a totally different experience for Rachel (and maybe, to a lesser extent, for Jake) than it was to the other Animorphs. The other Animorphs just lived through through the war. Rachel lived, through the war.
As for Tobias, I don't see his mother picking up where she left off and raising him. She had a chance to be a good mother in the later books after they'd been reunited, and she didn't really seem to jump at the chance. Other than saving his life that one time, she seemed mostly to ignore him. Who knows if she even looked for him after he disappeared after the war? She sure didn't look for him when he disappeared the first time.
To get back on topic, I totally agree with Blue about Cassie. There's no way that someone has to go through all that, having started out as a good person who knows right from wrong without fail, and comes out the end as that same good person with the same strong moral compass. KA tried to portray Cassie as something 'greater than human,' I think, but it only ended up coming off as idealistic and unrealistic.