I remember seeing an option at the Imperial Vienna where you can have the butler to join (come with) you when you go out to shop (2-3 hrs?). He will take you to the right places depending on what you want to buy... will carry the bags for you and will settle the cost on the hotel bill which will then just get charged to the room.

I remember this only being made available for those staying in the most premier suites... but if it was available at a cost, I would consider as it would be an experience like no other.