This. It's really not that hard to tell my TA what cabin I would like (I always give her a few options in case my first choice is gone by the time she gets it - which is always within 24 hours, usually less...but I'd rather give her more just in case).
And as I've worked with her, she has gotten to know what I like, so honestly I hardly NEED to tell her any more as she can look at availability and book what I'd prefer.