Sixty (plus) prof here who usually gets to sit on the hiring committees for this sort of thing. As others have pointed out, a lot depends on the culture and size of the institution and on the particular job and field. Generally smaller institutions are less formal than larger ones, and science/humanities are less formal than business/engineering folk, but there are always exceptions.
My suggestion would be to wear the suit with a soft blouse in your most flattering color. Wear lowish, fairly conservative, well-polished pumps instead of boots; your shoes need to be ones you can wear for 8-10 hours comfortably, otherwise your discomfort will show on your face during the presentations and meetings. A tall, well-polished, refined boot can work for some people, but it is a more risky proposition. Keep accessories minimal and refined. Be impeccably groomed, right down to your nails. If you have long hair and tend to flip it around when nervous, tie it back. Use a lip balm so you don't keep licking your lips. Everything will be noticed, most often by the least groomed person on the interview committee. Leave the backpack at home and use a briefcase to hold your papers and equipment; leather is nice, but a classic, dark zippered nylon case is just fine.
Find room in your briefcase to toss in a cardigan and a scarf. If, once you are there, you think the suit is too formal, you can take off the jacket and scrunch the sleeves of your blouse for a more casual look. If the room is cool, you can add the cardigan to finish the outfit or wear the jacket with the sleeves rolled up. If the room is warm, and your skirt/shirt outfit sans jacket looks unfinished, add the scarf. If every other female candidate is wearing a dark suit, you can also use the scarf create a more memorable image--"that candidate with the red scarf" idea. If you spill something on yourself during lunch, you can always replace the shirt with the buttoned cardigan--a godsend if you have an afternoon presentation since salad dressing and silk blouses seem to have a positive affinity for each other. If you will be having dinner with your interviewers, you might also want to consider adding necklace, or interesting earrings, to your skirt/blouse combo for another look.
If the interviews extend into a second day, a pair of trousers that work with your suit jacket and/or cardigan can be a nice change because the interviews tend to become less formal as both parties get to know each other.
And, most of all, remember that you wouldn't be going through this process if people didn't think you were a credible candidate for the position. Concentrate on your audience instead of yourself and help them see how you'd be an asset to the department. Be kind to other candidates and, if something doesn't go right, smile, fix what can be fixed, and then move on with confidence.
