We are planning on flying into Milan in April and hiring a car and driving to Zurich (taking about 5 -6 days). Can anyone advise on the best route to take and what sightseeing we should be doing along the way and approximately how long we should spend in each place. We would appreciate any suggestions. Many thanks

Before you start to plan your route, you should check the fineprint how steep the penalty charge will be for cross-border rentals. It may be substantially cheaper to take the train from Milan to the first stop in Switzerland and rent from there.

http://www.viamichelin.com/web/Routes I was just going to say the same thing unless this is a rt.

Yes, get the car in Lugano and save a bundle.
I would make two stops---Luzern and the Berner Oberland---the best of the SWiss Alps.

Drive over the St. Gotthard to Andermatt and from there over the Furka and Grimsel passes to Luzern. That will give you a full taste of the Alps.

http://www.flickr.com/photos/mksfca/...th/4207016222/

Thank you all for your input it is much appreciated and I didn't realise there could be weather problems that late in April. I think I should now look at hiring the car in Milan as you said and doing the Lakes area etc, would five days be suitable for that or should be make it shorter and then take the train the Lugano and spend a few days there exploring, or go straight to Zurich on the train. Many thanks

The pass roads mentioned by Michael will all be closed because of too much snow and danger of avalanches in April.
You can easily spend 5 days around Lake Maggiore (only a few miles from Milano Malpensa airport), Lake Orta, Lake Mergozzo, Lake Lugano, Lake Varese, Lake Como and Lake Mezzola. Everything will bre in flowers in late April:
subtropical plants in botanical gardens like Isola Bella, Isola Madre, Villa Taranto, Isole di Brissago, Locarno, Lugano Municipal Park, Villa Carlotta, Villa Olmo ....
idigene plants in the nature above the lakes: white narcissus, lilies of the valley, brooms........

For Switzerland, you may have a look at
http://www.myswitzerland.com/en/home.html
http://www.swisstravelsystem.ch/en/
http://fahrplan.sbb.ch/bin/query.exe/en

Too little time and too many choices.