Excellent plan. Lots of places to stay - hotels, condos, etc... - Homeaway.com (VRBO) offers many options (beware the add ons - maid/fees/etc). Short drive to Lake Mary and Lake George (all paved). Trail heads to Crystal Lake, Mammoth Crest, Duck Lake, etc..... Mammoth Crest trail head is ~9K', with climb of ~1,500' up to the crest. Approx. 4 miles round trip. Nice warm up for Whitney. Two nights there, plus one night on the trail should put you in good shape for acclimatization.
You might want to consider flying into Las Vegas. Could be cheaper, and certainly closer/shorter drive.
