When buying a cage for your pet, you have to remember that this is going to be his home. You have to decide how you are going to “furnish” it. If you are going to put a hamster wheel and a water bowl in a hamster cage, you need to make room for your hamster to have his “special corner” to do his business in and enough room to dart around without knocking his bowl over. You can also purchase a bottle that attaches to the side of the cage, which is a more sanitary, but noisier option. If you are buying more than one hamster, make sure there is enough room for them to have their own corners and dry places to sleep in.
Guinea pig cages are notably larger than hamster cages. Like a hamster cage, you have the option of using a water bowl or water bottle. If you prefer to keep the cage drier and easier to clean, it is probably better to use the water bottle. Don’t worry, your guinea pig will figure out how to use it! Leave enough room for a salt lick and for him to have his corner to do his business in and have clean areas to sleep and run around in. When guinea pigs and hamsters get excited, they love to scurry around their cages and kick up the “bedding” in their cages, which will end up on your floor or carpet, and you probably prefer to have dry pieces than wet, right?