Crystal Crag is a short hike from the parking near Lake George. Perhaps 1 one mile to Crystal Lake from the parking, then another 1/2 mile to the Crag. Not sure if there is class 2/3. I do think you might find class 4 on the south side.
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Another option would be the hike up to Mammoth crest. It offers great views, and good acclimation for Whitney. Same trail head, but turn right instead of left as you near Crystal lake (small sigh, easy too miss). Total distance to the crest is approx. 1.75 miles.
If you have time and want to go further do the "loop" along the crest, down into the Deer Lakes basin, out the other side to Duck Lake, and trails back to Lake George. Or, hike to Lake Mary. Then along the road back to Lake George. Total approx. 14 miles. You might catch a ride from the Duck Lake trailhead to Lake George. Saves 2 miles or so.
The climb out of Deer Lakes Basin provides some class 2/3.