I really enjoy Arts and it's pretty formulated to what I want to do after uni so I'm studying Politics and International studies. I enjoy learning languages and want to work overseas so I'm studying German. I sometimes think I could probably transfer to Arts/Law but then realise I'm only thinking that because it sounds more impressive, not because I'm actually interested in it or it would help with my career after uni. I guess an issue with a lot of Arts students is they choose Arts because they don't know what to do with their life, and this can leave them stranded afterwards...
It really depends on if there's specific subjects that are going to interest you/add any depth to your other degree. I know a lot of Arts/Law students who do International Studies or Politics because it can be useful to studying law. You could probably incorporate a range of units in with a business degree.
Do you know which subjects you would consider from Arts?