The sizes you mentioned for the flooring: 11mm or 8mm are not "widths" of the plank. It is the THICKNESS of the plank. Technically the thicker the laminate the "nicer" the laminate.

Small rooms do well with lighter flooring. And please do not use laminate in the kitchen. It won't survive for very long. If you are going to do it, please purchase enough laminate to REMOVE AND REPLACE the kitchen TWICE. That way you can have the same floor throughout the house even if the kitchen is severely damaged....and the potential is VERY high that laminate in a kitchen will NOT survive a rental situation.

Remember: in a rental, the life of a floor = 7 years on average. Laminate in a kitchen averages 3 years. That's why you want to buy enough laminate to install the kitchen TWICE....it's the only way you can get it to "live" for the full 7 years.

Have fun.