Thanks for all of the wonderful book recommendations. You guys are awesome; I knew I could count on you smart people to point me in the right direction.
I actually didn't end up getting anything any of you had specifically named, but your advice was definitely a big part of how I ended up getting what I got.
For my brother, I felt the McSweeney's suggestion was most fitting. Naturally, he already has a subscription to that (I think that officially means my brother and Dylanite would get along), but I saw they also had books on the site as well. I figured anything Dave Eggers recommends would be good, and I came across a novel I think my brother will enjoy titled The Children's Hospital by Chris Adrian. Anyone here read it?
There were definitely a lot of great suggestions for my mom, but I especially liked what I saw re Dewey. Except, with getting my dad and brother heavier works, I didn't want to make it seem like I think she's dumb (she wouldn't think that, I just overanalyze, and yes, I know I was the one who asked for something lighter). So I grabbed The Namesake by Jhumpa Lahiri, which I enjoyed, as well and headed to the Pets section to find Dewey. Except, I couldn't find it. I did see another book in that section, though, called Woman's Best Friend with short stories by female writers about their dogs. Since my mom is more of a dog person anyway, I think she'll like it.
Thanks again!