Like the above, I would recommend rats, they are a total joy to have!
Yes, it is best to have rats in groups as they are very social and it would be best to buy rats from a breeder because rats from pet shops (Like mine) tend to have RI's or just health problems proping up in their life consistantly.
Rats LOVE to have a cuddle and come out to play! I have never been bitten by one of my rats and it's very rare.
You can even teach them tricks! I think rats would be the best for you, even though they were not listed above. I know their tails put people of, but they are actually quite fastinating!
I would recommend getting males for a first time because they are more laid back and females are prone to tumours.
It sounds like rats would be the perfect pet for you. They are nocturnal animals, but mine have learnt to fit into myroutines and they soon know what time it will be for dinner or play time because they will be jumping up at the cage expecting you LOL
Take a look at the mouse and rat conversation and see what you think, or there are some good websites, like:
Hope my information helps