Rats are nocturnal really, and noisy. Mine make the same sort of noise as a small toddler running about upstairs every night... They also need large cages. But yes, they do make fab pets and if you just have two girls, there shouldn't be any smell. They also do not bite.
If you have room for a 2-3ft fish tank that you can put a wire mesh on, and find some, you might want to consider Multimammates. They are larger than mice, smaller than rat. Females will live happily in pairs or groups and are less likely to bite. If you get them from a very young age, or from someone who has handled them well, they shouldn't bite at all. They have gorgeous, really, really soft fur and are usually up and about during the day. They don't smell at all and are best kept in tanks as they will chew out of a plastic cage, so no problem with shavings getting everywhere. They are more bitey than a hamster, gerbil or rat (which in my experience do not bite at all except in very rare circumstances) and have a reputation as such, but I have found youngsters do not bite and can be taken from Mum at 4 weeks so yuo can get them young. They aren't as skittish as mice and can be picked up carefully by the tail then placed on your open hand. They don't like to be picke dup n a cuppe dhand and are most likely to bite if picke dup like this. (I have never been bitten whilst picking up/holding them, but my males, who aren't especially tame will occasionally fly acros the tanks at me, they are territorial)
Some pictures: (these are about five weeks old and my first group. They ate out of that 'cage' in two days, hence the glass tanks now)
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