Osaka in five nights!

I realised in the weekend that we have two three-day weekends coming up and no plans, so I have booked Jeff and I a hotel in Osaka for Friday-Monday.  We have no definate plans other than visiting the aquarium (zoos and aquariums are always top of our list!).  As it's still very (very!) warm, we intend to spend most of the day in air-conditioning, eg. our hotels or shopping malls, only emerging outside once the sun goes down.  Cities are good for this type of thing.  We have only spent one night in Osaka before, so it's very exciting!  Bar hopping and shops with English, here we come!!  :D