We are leaving Friday for 10 days in Paris and Normandy. From weather.com it seems to be in the high 60's in the day going down to the high 50's at night. I was going to take cropped pants and sandals, but am thinking I am better off with warm up suits and closed shoes, tho that seems wintery for the middle of September! Any suggestions would be appreciated.

Just bring a combinations of long and short sleeves blouse,slacks and capris ,bring a light jacket, close in shoes and sandals, warm up suit in case the weather get too chilly , especially in Normandy,also bring a foldable umbrella, you may need it in both places.. other that that use your common sense.
Have a fabulous time and enjoy France,
Ciao,
kismet

http://www.weatherbase.com/

I do not recommend a warmup suit, unless you are striving for the hip hop look, anywhere in Europe.

I should have not said "warm up suit"...I have dressy knit pants and jacket...not the nylon type used for jogging...just the style of a warm up suit..one is black velvet and the other is a cotton knit with a jacket with a stand up collar...not hooded or anything like that. Velvet seems too wintery..that is why I asked.

I would personally suggest closed toe shoes unless you can stand dirty feet or better yet wet feet. The streets of Paris are dirty and my feet were covered in dirt and grime after a day of walking around in sandles. It was worse when it had rained. I'd also suggest you have a sweater or something to layer. That way if its too hot you can take it off or if your cold you won't freeze.

Maybe you're from a Southern state where it's still very warm in Sept., but it is really more fall-like in feeling. I live in Wash DC which is about same temps as Paris, and it is already feeling of Fall in the air and sandals are kind of out of place. Current Paris weather reports are for highs around 70-75 in afternoon and lows around 50 at night.

Sandals are more for summer, I wouldn't even take sandals to Northern Europe in late September. I don't think cropped pants are necessary, either, although maybe one pair if you think there might be a heat wave, but I'd take more regular-length pants. I would not take a warmup suit or wear one in public anywhere, I'll admit, I don't own one and wouldn't wear one out in the US. I think that is for use in a gym or exercising, probably.