Re what Vicki said... We were there early June 2004. Crater Lake is gorgeous and worth a visit even if you have to climb the snowbank to see it. The road around the lake was closed, under that 8-10 feet of snow Vicki mentioned.
Here we've climbed the snowbank to view the lake.
This is across the parking lot. Those are the doors to the snow tunnels to access the restrooms that are in that building behind the snowbank.
And this is the Visitor Center. Accessible through a snow tunnel.
The road to get to this point was cleared, as was the parking lot. Any two wheel drive vehicle would make it just fine.