Sept., I have been on the Imagination - in fact all of my cruises have been on Carnival. The recommended tips will be added to your Sail & Sign card, which is what you use to buy anything on board the ship, as a room key and also as your pass to reboard the ship in ports. If you want to change the amount that is added in the way of tips, you have to go to the Purser's desk and have it adjusted. You asked about changing rooms - I am not sure of the answer to that, I think Carnival would answer you honestly if you called and asked them. It would be better to book 2 in each room, rather than 1 in 1 room and 3 in another, because the person who is booked in at a single is going to pay a premium price, as the rates are based on 2 to a room and she may have to pay for 2 people for her cabin. Several of us here use the same trip planner at Carnival, Jennifer Martins. If you are interested in talking to her, you can PM me and I will give you her number.