Rob: I've hiked/skied the High Route 7 times in all seasons with lots of different route variations.
Getting to Paintbrush Divide requires some Class 2 scrambling and exposure to afternoon thunderstorms, so do it early in the day if you are going in July/Aug in the midst of a T-storm pattern cycle.
From Granite Lakes Basin, leave the trail and veer upward to the saddle immediately N of Littles Peak. Climb to the summit of Littles. This is all Class 1, easy stuff.
There is a bivy wall built on the summit of Littles, and in good weather, it's a pretty spectacular place to spend the night. Observing alpenglow in the evening and morning from that vantage point is awesome. Also, there is year-round water (even in relatively dry years) in small snowmelt ponds, and a small tarn, within a 10-15 minute walk from the summit, to the E. Here's a pic of the bivy:
You now have two options. Both of them are Class 2 scrambling, and if it's wet, will require some care.
The first is to navigate to the top of a gully leading directly down to Lake Solitude. The gully is an obvious topo feature on a 7.5 minute quad and is NNW of Lake Solitude. This TopoZone map is centered on the top of the gully:
Descent Gully into Lake Solitude
The gully is fairly steep and requires some scrambling with the use of hands. In the early season (June-July) it is filled with snow and pretty dangerous. In the morning you need crampons and an ice axe and skills to use it. In the afternoons it is soft snow over loose mid sized boulders and is a killer ankle breaker.
Later (July-August) it can be wet, and choked with willows (provide good handholds), and can be slippery. Later (August-September) it is dry and quite pleasant, considering the alternatives!
The other option is to follow the E Ridge of Littles Peak (Class 1) all the way to Paintbrush Divide. There are some Class 1/2 steep gullies descending from the ridge down into Lake Solitude that you can drop down, but in the summer they are pretty slick with low growing willows. If you go all the way Paintbrush you'll have to negotiate a few Class 2 moves over and/or around some rock gendarmes (loose) on the ridge.
From an aesthetics point of view, the gully descent into the Lake is spectacular because you get to drop into one of the most beautiful lakes in the Tetons.
The ridge walk to the Divide is equally nice, because you remain high and face to face with the Cathedral Group (Owen, Teewinot, and the Grand) - it's like you can reach out and touch them.
Here's a pic of the "east ridge" of Littles as it falls away (to the E) off the summit plateau. Note that it's a pretty flat ridge - very nice walking. There are only a few bumps that require scrambling, it's not hard. It's longer than the gully descent into Solitude. If I had time to burn and the weather was good, I'd consider the ridge. But if I had to bail off the summit of Littles to avoid exposure to lightning, or if visibility was bad, I'd probably descend the gully.
It's a fabulous trip - let me know if you need more beta.