Wow, what a stunning hike! As you hike, you face the Mountain and it gets bigger and more beautiful with every step of the way! We hiked up the trail via Sourdough Ridge and Frozen Lake at a moderate pace and reached the first Burrough after about 1 hour and the second 45 minutes later. A pretty clear trail to the third Burrough exists, though it is not marked in the maps and isn't written about in most books. Just follow the trail as it continues past the second Burrough and take a right as you dip down in the little valley. But be warned, its a good hour beyond the second burrough, or, as we estimated, 1-1.5 additional miles each way. You will be rewarded by the fine vistas at the end, gazing at a mountain almost close enough to touch.
Most of the snow fields have melted. To get to the first burroughs the trail is totally dry, to get to the second there are two small and easily traversible fields, 15 feet or so wide, and not near any dangerous crevasses. To get to the thrid burrough you will have to cross a larger snow field, but again it is not dangerous or near any place you could fall off. Go slow and use good boots and a hiking stick, and you should be fine.
As you come back, the trail forks to the right just as you reach the first burrough. You can, at this point, follow the right hand fork along Sunrise Rim and through Sunrise walk-in campground. But, a small and trecherous snowfield remains along a sheer rocky field. I didn't think this was a very safe crossing and would not advise people to take it. If you do, you will enjoy alpine meadows and also be followed by mosquitos and flies. Otherwise, the rest of the trail has a good breeze blowing most of the time, which keeps bug bites from being an issue.