I want to replace my master bath vanity, sink, shower/tub. How do I start? I went to Lowe's and looked at vanities and showers, picked up brochures, etc, but how do I get something that fits the space I have? Obviously, showers and vanities come in different sizes so how do I find one that will fit my current space exactly?

Also, for the shower, I do not want to go with one of those tub and shower systems that just goes over what you currently have. I want the old stuff out and the new stuff in.