ok for the day visit you wont have lots of time so i would just stay near the centre - you probably want to be in the golden triangle where some
of the smarter bars and restaurants are. If the mrs likes shopping head to the pavillion. I would do some of the main sights such as
the petronas towers, merdeka square and chinatown - which is great for food.
For the longer stay try to book tickets to the top of the petronas towers. Unfortunately you have to go early to get them as they are limited.
I think they start at 8am but you have to be there earlier to get them. During the week should be a bit quieter. If you cant be bothered just go the
the kl tower instead which isnt as tall but has good views as well. I would then get out of KL for a day. Maybe go to the batu caves which are
quite close or the genting highlands which has a cable car above the rainforest as well as a casino. A couple of other places in KL are the
central market for souvenir type stuff and lake titiwangsa which has good views of the city. Malacca might also be worth a day trip.
Will be hot in january but might have the odd rain shower also. Dont think you will need any injections for a short stay. Just avoid the mossies.
Not sure about bargains. Shopping centres here arent that cheap but the locals get much lower prices elsewhere. Its not dear though except
for a beer in a decent place. You shouldnt get ripped off as long as you have your head screwed on and dont wave your money about.
The locals are quite friendly and its a pretty safe place. Just google some of the places and see what you might like.
Will pm you also. Hope that helps.