Nicky - were you talking about your experience on the Zuirich trams? I have only been on them a few times with the buggy but found a lot of them still have steps up them. Here in Basel, nearly all trams have at least one low carriage for easy access ... although a year or two back I did once have to wait for another number 2 tram as it had no low carriage. This is the only time that happened to me in Basel in the past 5 years.
I have had no problems at all in Basel - do exactly same as Mimi1981 and rarely find I cannot get on a tram - and actually found my big traditional pram and 3 wheel pushchair better for getting on and off than my tiny compact about town zapp - because the wheel frame in bigger buggies is longer and allows you to swivel between kerb and tram floor whereas often the quinny zapp could not stretch between the kerb and tram ... particularly at stops on bends.
My thought would be wait until baby is a bit older and you have tried out the trams etc for yourself before buying a new buggy - then nip over to France or Germany to get one nice and cheap.
Basel is awesome for big buggies. I have trekked around the trams and buses of Basel for the last 18 months with a side by side twins buggy, and pretty much never had a problem. The majority of buses and trams have no steps and a nice old person/pram deflate option that lowers the bus when it opens the doors. A few of the old stlye trams have steps, but they always have one carriage for prams and wheel chairs, which work fine.
I have also found people here to be super friendly, helping on and off (not that u need it as it's manageable alone) but nice anyway. And unlike other countries which have rules, eg on how many buggies can go on a bus, here u can cram as many on as u want.
Things to b aware of- rush hr can get busy, so u either need to do the push and shove method, or the "have pity on my, I am a harried mom" approach, or just try to avoid busy times.
Coming from London and traveling extensively with the double buggy these past months, Basel wins hands down for most pram friendly public transport I have experienced. So don't waste energy worrying about this! And make sure you check out bcd so your wife has nice baby groups to go to when she gets here!
Actually, it depends on the tram line you use. Lines 1 and 2, heavily used by commuters, usually have old trams. Most of the other lines have decent space for prams.
If it gets crowded and you need to get off, it's a matter of asking something like: "Hallo, ich muss aussteigen" (Hello, I need to get off), although it may no be necessary as when they see you requesting the bus to halt they usually make room. Most people has good manners and will let you in/out.
The trams here are excellent. I was on a number 3 the other day and in the low section there were 5 pushchairs crammed in. Plenty of space and someone will nearly always hold the the door button for you.