Actually, your problem might be returning to CH (if you are bringing gifts back). I have never been stopped leaving CH, but coming in, it is a crapshoot. I would bring your receipts with you to prove that the items were purchased in CH.
We took the TGV to Paris for Christmas last year with loads of gifts (for us, so we brought them back), and no one checked us in either direction.
Last year when we drove to Germany the guys checked our passports and asked me "anything to declare". When I said "no" he asked again "no presents either". I simply said "below 200 Euros, five cigars should be within the tobacco limit just as one bottle of wine for alcohol." He let us go immediately without searching the boot.
As I thought, it a lottery we go over to FR a lot and recently the FR border guards seem very diligent. Recently way into France there was a mandatory customs check (30k inside France) checking every car/truck.
The problem is the Swiss do great wrapping, coupled with the fact I am crap at it and it seems a shame to unpack. Is the French tax payable VAT over and above €300?
I did read somewhere that there was some sort of amnesty for Christmas presents - but maybe that's wishful thinking?
I would wrap them, I had a real car load last year from all our family in the UK coming back into Switzerland. When I got stopped at customs and they looked inside it was presents for the family. They could see what they were and weren't too bothered in the festive season. They just asked if I had any beer!!! Dont get too paranoid about Chrismas presents.
Friends are coming from Belgium to Switzerland, most likely with (liquid) supplies for New Year's celebrations. Are the rules any different from the more usual question here of someone moving to Switzerland or a Swiss resident coming back in? If a group of 4 adults is in a car, do they each get the full custom allowance of 2l up to 15% and 1l beyond 15% ?
Thanks for any insight