One traveler or two travelers? If one, the roomette is adequate; the bedroom is luxurious (private bathroom, y'know). If one adult and a child the roomette is do-able; the bedroom gives room to spread out. Two adult travelers in a roomette can be done (I've done it with my own father around the Western U.S.), but you're better advised to spend the extra for a bedroom if you can afford it (in 2016, I couldn't!).
And just in case you weren't aware of it, there are two different trains that go between Chicago and Los Angeles: The Southwest Chief and the Texas Eagle. Both have the same fare structures which can be seen. So you could not only take different rooms on your round trip, but different trains for variety. Fares for both trains both can be found here: Long Distance Train Coach & Sleeper Fares (Buckets)