Engelberg looks like a good idea. Other options might be Rigi or Hoch-Ybrig. You're lucky, there's a lot of snow this winter and even the resorts that are not that high up in the mountains will still be open in late March.

One big advantage of the train is that it saves to time in traffic jams up and down the usually long, narrow and winding roads to the resort towns / lift stations. These access roads can be gridlocked with ski tourists, but that is only a problem if you go on weekends.

If you bring your own gear, you should definitely get a car as I have found it to be a big hassle to lug skis, poles, boots and warm clothes around in the train, especially if you have to change trains several times each way.