I agree: less is more. I don't really want to know about the personal life of an employee or a prospective employee. As for the lab tech position (I'm a scientist, so maybe i can help). You know that science dress is often different from professional dressy. As a woman in science, sensible dress pants or even a dress suit are fine. I would recommend wearing sensible shoes - they may take you on a tour of the lab and a) you want to be comfy walking a fair bit and b) you don't want to have strappy heels on in a lab. Also, you have to strike that 'science dressy' balance. Don't dress like you are interviewing at a law firm. But, don't dress like I do for work every day: jeans / button down shirt. I have been in depts where I have heard other scientists laughing at an interviewee for dressing too much like the business world. Remember the 5 is enough rule: watch = 1, earrings =2, ring on your finger = 1, glasses =1 all of those = 5 pieces of jewelry. I think this rings especially true in science. You are also applying for a position with the city - I'm guessing there aren't too many labbies there; so you will have to address a broader audience than if you were applying in academia or a pham company. Here's what I would wear: dress pants, button down blouse, bring an appropriate jacket and coat/hat/gloves as necessary. I would wear closed toe shoes that are still fairly dressy - maybe black ballet type flats. I would keep my hair and make up simple and remember to ... SMILE! Be positive! Your CV obviously shines because you got the interview. Keep that in mind: they like you enough to interview you; now you need to gel with them. You don't have to dazzle them with your scientific prowess, but make sure you know what they are up to so you can ask appropriate questions.

Good luck! You will be golden