To summarize, most skiers will be most impressed with Squaw and Alpine Meadows, so stay up north to ski those areas. My timeshare is next to Heavenly and I rarely ski there, opting to go to Kirkwood most days. I prefer more wide open areas, than the runs cut through trees. I do ski Heavenly on days it is snowing.
I would really recommend that you have a awd vehicle, as dealing with chains is crap. As has been correctly said, in most cases the west side drive from South Lake is open to drive to AM/Squaw and it takes me about 70 minutes door to door. That is a beautiful drive if you decide to do it. In all my years going up there in February, that road was only closed once due to 3+ feet of snow from a recent storm.
Have a great trip