There is a fire going that's sending smoke in different directions each day. If i were you, i'd have at least 2 completely different plans ready, one for Lone Pine and one much further north, so you can adjust depending on where the smoke is. From Mammoth, a great short hike for views and lakes is to head up the Lake Basin, start from Lake George, and take the trail up to Mammoth Crest. Further along you can drop to Deer Lakes if you have time. The other Lake Basin trailhead, Coldwater, has more lakes but fewer views. Both make great starting points though.