We are going to be staying in Grindelwald 12/22-1226 and are not packing our ski jackets/pants due to traveling/packing concerns. Is there any place in Grindelwald that rents ski jackets/pants for adults and children should we decide to ski for a day? TIA!
In my experience, most ski shops also rent ski clothes. I had to do this some time ago when I left my jacket on the train. Shop rented me a parka for a couple of days before SBB located my jacket and sent it to me at Wengen station for a small service fee.
Of course, taking your ski jacket as your primary cold weather coat is a good idea, but they also have pants, goggles and gloves you can rent as well.
InterSport is the big sports chain in much of Europe including Switzerland: https://www.intersportrent.com/en/ch/skirental-grindelwald
You could correspond with the Grindelwald stores as to clothing rentals in addition to equipment rentals or check the specific store's website such as Graf Sport's rental page: http://www.graf-sportrent.ch/media/archive1/Mietpreise2016.pdf
Jacket & pants @ 17/day, helmet @ 9/day etc
Given that you are planning early winter travel, why not use you ski jacket as your insulation layer jacket? And you may want to also pack your base layers for walking around in a winter environment. That would leave only needing to rent ski pants and helmet.