Sorry for the delayed response.
I make frequent trips to Switzerland, and travelled to Europe from the USA on business for many years, until 2003 and 2004.
I never found the best way to get good rates in Belgium or some other countries, but I did find what seemed to me to be the best way for Switzerland.
Unless this has changed in the past few years, bank exchange rates in Switzerland were and are regulated, and among the best. Rates at the currency exchanges at the larger train stations in Switzerland are also relatively good. Smaller (manned) stations may not be so up to date, where the ticket agent also handles exchange. But, it is good to know they are there (if you are near a manned station.) . Depending on what your US bank charges, an ATM can be as good, or similar for the exchange rate, but will likely have a fee.
The fee may be fixed...not related to the amount exchanged.
So, contrary to the advice from Annika and Arno, I always change USD at a Swiss bank exchange booth (or Swiss bank ATM) at Zürich airport. At busy times, there can be a short line, but compared to the awful exchange rates that you quoted, you are way ahead. That is the pattern I have developed over the years.
I think that one bank still has a "two-way" window arrangement , opening on the luggage claim arrivals area where the carousels are, as well as opening just outside the luggage claim/ arrivals area, in the main part of the station. There are ATM's readily available in both areas.
The Swiss banks want to earn their exchange fees from travelers, so they try to make it convenient. You can do it with a credit card, or with a debit card from your bank, or from cash.
When I fly in from the USA, I typically carry one or two thousand dollars in cash for a 10 day to 3 weeks trip, and exchange it all right away. I travel a lot in the less touristed areas, and the cash is necessary. I don't carry it all in one pocket. Switzerland is not as safe from theft as it was in the 80's, but it is still reasonably safe from petty crime. After my trip, if I have any CHF left, I simply bring them along on the next trip. Even converting them back to USD is not terribly expensive, but i don't have that problem.
As much as possible, I pay hotels, train tickets and restaurants with a credit card that has no exchange fees, and on which I know the rates. The means my AMEX card and my particular Chase VISA card (there are lots of others now.) I ABSOLUTELY refuse the more and more frequent practice of letting the merchant/ credit card company do a conversion at unknown rates, and give me a slip to sign denominated in USD.
Most hotels and restaurants in main cities will easily accept Euros ( you get change in CHF) or USD ( same for change.) Exchange rates are whatever they feel like. I have stopped doing that. In the 80's. I sometimes did.Since the use of credit cards ahs been common, payment by USD has diminished.
In most tourist regions, credit cards are accepted. In the countryside, sometimes cash is the only option. Check if you have any doubts. Around St. Moritz, there are still a fair number of cash only places.
The banks in the USA are not regulated on their exchange rates, and their rates and fees vary. So, the example you quote is certainly not the best. The best spread I have seen is around 2.7 to 3.0 %, not 7 1/2 %, and with no fees. And, purchases with some USA credit cards in Switzerland have no fixed fee, others have a fee of USD 3.00 for each transaction. . That hurts if you do a lot of small transactions.
On my Chase Bank VISA card with no fees, the exchange rate is about 2.7% to 3% in favor of the bank ( vs. published bank rates.) AMEX has similar rates, maybe just very slightly better, and some of their cards now have no fees.
However, if I use an ATM to withdraw money from my Chase Bank account, I am charged a fee (around $3.00, I recall) , plus similar interest rates. (2.7 to 3.0% extra for the bank.)
Under no circumstances should you use the "Travelex" booths in US Airports. Highway robbery. You can use an ATM at Zürich airport and come out way ahead.
So- if you change in the USA, you have to work to find good rates/fees. They exist. (You might check with AAA...they do currency exchange. I don't think that their rates are especially good, but they are convenient). If you change at an airport in Switzerland, the rates are comparable to the best US rates, easy to find, and a lot better that what you described.
If nothing else, you could exchange pocket money when you arrive (or even a little bit at a Travelex ;-( ) and then go to a bank while traveling. They are not uncommon in Switzerland.
Hope that helps.