Stream crossings aside, I would highly recommend that you structure your trip transportation-wise such that you are not committed to making the valley once you start.
The average (i.e., fifty percentile) seven-year-old is 4 feet tall and weighs 55 pounds, so I trust that your son/daughter is not going to be backpacking much, if any, weight. Even so, a 30+ mile hike over 4 days with the elevation changes involved (I get +3.3k and -7.9k when tracing out your proposed route using TOPO!) might be pushing it a bit for someone that age.
I would suggest that you see how things go the first two days and make a decision at the Vogelsang HSC whether to push for the valley. Even if you do, I would recommend that you follow Fletcher Creek down rather than Lewis Creek (since you start losing elevation immediately after passing the HSC, it is a bit shorter, and you avoid several stream crossings). If you decide to bail, then you can then use the Rafferty Creek trail to loop back to Tuolumne Meadows (and, if you have some time to waste, you can always do a dayhike around the Vogelsang area.)
Since the approach to Vogelsang from the E has lots of sun exposure, my guess is that you are not going to run into any major snow problems there by the time of your trip. The N-facing trail up to Vogelsang Pass is likely going to be another situation entirely.
I worry a bit (actually, a lot) about doing the stream fordings with a seven-year-old. For that reason alone, I would argue for you to considering just doing the Lyell-Vogelsang-Rafferty loop from Tuolumne Meadows. On that loop, I think that there is only one fording, across Rafferty, which may be somewhat challenging. (There should be two others, one stream flowing into Evelyn and another into the unnamed lake E of Evelyn.) At any rate, it wouldn't hurt to also carry along some ~5mm. accessory cord to assist in the crossings if deemed desirable.
Edited 1 time(s). Last edit at 07/02/2010 09:22PM by szalkowski.