My niece traveled to Switzerland this summer and returned with Coins: 1⁄2, 1, 2 & 5 francs. exchange centers in the US only take back Notes, where is the best place to trade these in?
Probably not the answer you are looking for, but the best place to exchange Swiss coins is in Switzerland. As you already noticed, banks and currency exchange offices usually only trade with bank notes and do not accept or give out coins.
It the value of the coins is worth the effort, you may consider looking in your neighborhood or area for Swiss people or people who are going to Switzerland, who might be willing to change the coins for you.
If you're feeling philanthropic, then the UNICEF's Change for Good program will take unwanted foreign coins. Most international airports have collection points, and some airlines will ask passengers for unwanted money. As you are in the US, then you can post them to
UNICEF USA ATTN: Change for Good Program 125 Maiden Lane New York, NY 10038