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I am assuming your teenage girls have their own cabin then there is normally plenty of space to hang items up but there will be space under the beds to store your suitcases so some items could be left in there. One thing though you do have a weight restriction, go over that and you will have to pay the excess or in some cases have to redistribute what is in your cases to keep under the limit which is 21kg per case.
Typo error 21kg per case should be 23kg - apologies.
On a non fly cruise the luggage allowance is alot higher than the above answers, it is maximum of 90kgs per guest as quoted in RCI brochure.
Fao HEAD in case you want to check allowance for yourself log on to royal caribbean.co.uk click on things to go then booking conditions download and info you need is section 2.5, hope this is ok.