What to wear for women 40+ working in offices

Question for women working in offices

I have some job interviews next week and I don't know what to wear. I have been working at home for 6 years! I actually have a lot of clothes, but now it's mostly shorts and short-sleeved blouses. I went to an interview a few months ago and wore black work pants and a top with a black sweater. I had a nice black Coach purse and black flats. Should I wear a black skirt and heels instead? Thanks! They aren't for sales positions, just customer service type jobs.