Since Atticus is her brother, Alexandra tends to support him because he is family--and the Finch name has always been of the utmost importance to her. If we can believe Scout's cousin, Francis, then we know that Alexandra cares little for Negroes.
"Grandma (Alexandra) says its bad enough he (Atticus) lets you all run wild, but now he's turned out to be a nigger-lover..."
We know that Alexandra was not happy with Atticus defending Tom, since Scout later overheard her arguing with her father.
"She won't let him alone about Tom Robinson. She almost said Atticus was disgracin' the family."
Alexandra refused to attend the trial, but she did seem sincerely disappointed that Atticus had suffered defeat. Alexandra seems to have mellowed even more when she hears of Tom's death. But it is her brother that she is most concerned about, not Tom.
"I can't say I approve of everything he does, Maudie, but he's my brother, and I just want to know when this will ever end... It tears him to pieces."
Alexandra never speaks much about Bob Ewell, but since she despises the Cunningham clan, we can only assume that she must feel likewise about the Ewells. She does warn Atticus about Bob's persistence, however.
"His kind'd do anything to pay off a grudge. You know how those people are."
Perhaps Alexandra's most telling opinion of Bob was one that was never uttered. In Chapter 27, she had a premonition.
... she stopped short in the middle of her sentence. She closed her mouth, then opened it to say something, but no words came.
" 's matter, Auntie?" I asked.
"Oh nothing, nothing," she said, "someone just walked over my grave."
After the children were attacked, Alexandra realized what her unexplained feeling had meant, and she blamed herself for not understanding the implications of it.
As for Alexandra's hobbies, she likes to socialize with other Maycomb women of high standing; she enjoys cooking; and she attempts to put her mark on Atticus' children--escpecially Scout, whom she hopes to somehow make more ladylike.
Aunt Alexandra thinks Bob Ewell is a piece of trash. She is afraid of him when he spits tobacco at Atticus' face. She classifies him in a group, just like she does everyone else. Bob Ewell is almost on the bottom of her class status ladder.
At the very bottom of her ladder is the Negro community which Tom Robinson falls into. She doesn't really take a position on his guilt or innocence, but certainly judges him purely on race.
The trial is something she seems to have mixed feelings over. She wants the best for her brother and doesn't believe it is possible that he could win. She thinks the trial is doing terrible things to the family, this is evidenced by her insistence that she move in that summer.
She likes to tell people what to do, classify them in her social ranks, and be a Southern belle to the best of her ability. That means dressing a certain way, upholding certain social standards, and holding missionary teas.