Are Swiss coins from the 1960s and 1970s still valid (legal tender)?

Yes they are — the fundamental design of Swiss coins has not changed much in the past 100 years, except for the metal content. Indeed, I once received change with a 10-centime coin from 1910. It looked exactly the same to a 10-centime coin from 2010!

Coins from the 1960s and 1970s are certainly still legal tender. However, you may be interested to know that the 50-centime, 1 franc, 2 franc and 5 franc coins were all made in silver until 1967, when the mint started producing coins out of a copper-nickel mix, which makes them slightly more valuable for coin collectors.

The 1 centime coin was produced by the mint until 2006 and the 2-centime coin until 1978