There is plenty of good water in the Loop. My favorite is Silver Lake, followed by Gull and June. Grant is a good lake, but difficult to fish if its your first time there. Rush Creek and the several small streams in the area are well stocked and all offer good fishing.
I recommend you pick up the book
California Fishing by Tom Sienstra. It is a great book to own if you are beginning to fish in the Sierras, and California in general. Along with solid fishing knowledge and area info, some campsites and accomandations are provided. There is numerous literature and online material on the Sierras, and you can never know enough when it comes to trout fishing. Best of luck and remember to dress warm. May/June can be suprisingly cold for those not used to the Sierras and coming prepared is the only option. And most of alll....have fun!