The boot in the CT200 is reasonable but it all depends what your wife's gonna be luging about, I get two large luggage bags in the boot without having to put the seats down. Its a flat floor job with storage underneath. mines the F sport so has a Sub enclosure on one side as well.
I have two kids that still use boosters and there's plenty of room in the back for them.
No road tax and 50mpg on avg, make it practical enough for me.
http://www.autoexpress.co.uk/lexus/ct/19458/lexus-ct-200h-third-report