COMMENTS
This is decent advise, but be wary of the fees for luggage on all the European low-cost carriers. If you are finally returning home after a long period in Switzerland, I assume you have a lot of stuff (as opposed to a vacation). If you are travelling rather heavy with two or three bags, then you'll pay stiff baggage fees PER SEGMENT. National/legacy carriers may or may not have caught on to the whole "charge more bags" philosophy. Definitely make sure you crunch all the numbers first.
Also, think about the hassle of de-planing, heading to luggage claim, grabbing bags, heading right back upstairs to arrivals level, checking luggage BACK in at the counter then going through security AGAIN in order to make your next connection. The margin for error, delays, etc., has now increased substantially. I'd say wait for the cheapest, yet lowest # of connections.
Good luck dude.
I strongly advise you check out the Canadian based charter services for this as you're travelling peak season. George mentioned Zoom, but there's also Air Transat, Globespan, and various travel agencies operating charters (such as Thomas Cook in the UK and TVU in Germany) and they *do* provide one-way tickets (in fact, most of them only do one-ways).
You don't say where you're heading back to in the US, and getting out of Toronto cheaply can be a pain, but some of the charters do go out west, especially Calgary and Vancouver. If you're based in the east though, certainly if you're vaguely between Toronto and Florida you're likely to be able to pick up a hire car with FL plates for no drop off charge.
Check the prices carefully; they're no frills flights and get very expensive when full, but if you can plan ahead I've found that a NCL->YYZ in August is about a quarter of the price of a AMS->PIT.