I belive that you can find that information on their web site, go to fleets - pick a ship in the Grand Class(Grand, Golden, etc) then go to staterooms, pick a cabin catagory and it will give you the dimensions. Then do the same thing for the smaller Sun Class Ships (Dawn, Sun, Sea etc)
As others have already said the Regal does have the largest standard cabins on Princess, I find the ship lacks many features both in design and layout and I will not sail her again. I wish the Sun and Dawn had larger standard staterooms.( I like both of those ships and feel they are "just right" in size and facilities.