unattended car drop off

First of all you positively DON'T need a car in Switzerland because their public transportation system is unparalleled. Your 2 kids will travel free with you wherever you go in Switzerland...bus, boat, gondola, rail, cogwheel totally free. If you absolutely must have a rental car then do definitely drop it the day before. The last thing you want to be dealing with before an early AM flight is a rental car return. Personally I would never ever drop a rental car at an unattended lot.

We've had to do an unattended car drop off twice (both times in Malmo Sweden) - this was with Hertz. We had no problem each of these times - worked well.

I've done it several times - Sundays, early mornings. I take pictures of the car from all angles when I leave it, just in case, but have had no problems.

We've done unattended dropoffs without problem. We actually had one problem with an attended dropoff, if you can believe that, in Iceland. In this case, we drove the rental car back to the rental office, a rental company employee drove us back (in the same car) to our hotel, and then he drove the rental car back to the rental company. Apparently, on his way back the car got photographed speeding. A bill for the ticket amount was sent to our travel partners here in Seattle (it was rented under their name). They responded by saying send proof that it was them behind the wheel (as opposed to the employee). The issue was dropped.

I've done it. It's better if the local office has a key drop, but I did it once at an airport parking lot (in Larnaca) and left the key on the top of the driver's side front tire, per instructions. No problems.

I've had an issue once. I had to use the Europcar unattended dropoff (with key drop) at the Edinburgh airport. Only after my return to the US did I learn that they had somehow not clocked in the return until the following day, and had charged me for an extra day plus fees. They eventually dropped the extra day's charges, but only because I still had my original boarding pass, and thus was able to prove when I had left Edinburgh. I should mention that I had rented through Autoeurope, and they were instrumental in helping me resolve the problem. I guess my takeway was to always save my boarding passes.

Thanks for all the replies, sounds like its a relatively OK thing to do. Beats losing an afternoon traveling to/from airport the day before to drop it off. Plus trying to find a way to get eveyone to the airport the next morning. Any comments on best car models would fit us? Thanks
Rich

A station wagon is likely to be the best choice: it can accommodate a decent amount of luggage, but it is way cheaper than SUVs and - more important - easier to maneuver and park within city environment. Parking spots and lane width are narrower in Europe than in US, so a SUV is usually a bit oversized and gives you headaches in certain places.