I used to have a lot of problems with annoying neighbors with practicing in apartment living. The biggest problem is that the bass sound is very difficult to keep from going through walls and structures. Even if you mute the bass like crazy, you can still get that "woof woof" sound coming through the walls, floors, and ceilings.
I used to use a combination of heavy rubber practice mute, towels in the F holes, a towel under the fingerboard, under the tailpiece, and one balled up between the feet of the bridge. This doesn't completely mute it, but I always found that this was as soft as I could possibly get my bass for arco practice, and I didn't have neighbors bothering me about noise once I started doing this.
Even though it is technically legal to practice during the day here in Chicago (as well as NYC and other cities), that doesn't stop neighbors from pounding on the floor/ceiling/walls and calling the cops. Even though you are in the right, you can still have a miserable time with neighbors.
I hate neighbors.