1) Below the diversion, class 3ish.  Don't know if it's worth it, never done it.

2) Middle Section, Class IV - V.  Go up the big hill from Lilloet, TO is down a dirt road, near the snow gates, PI is at the first bridge crossing the creek.  The run is down in a huge scree canyon.  Good mix of IV and V drops.  Landslide section is always changing, and has some ugly spots.  Rocks are "fresh" and sharp.  Don't recommend the run for Class IV paddlers.  Scout the canyon at then end, to make sure there's no wood, and see the final drop.

3) Upper Section, Class V - VI.  Late late season, need very low water.  Heavy action.  Make sure you want it, before you start.  Run is way down in there. TO is at the PI Bridge for the "Middle", and the PI is further up the road.

4) Upper Upper Sections, Class III - IV+, depending on where you put-in.

 

Levels should be good in August for the Middle Section.

 

Not sure how the flows will be for the Lower Section.  You can see the end of it before it gets to the Lilloet.  BTW, there may be another smaller diversion in that stretch, but you'll see it when you're heading up the road.  I'd think you could do the lower at 1,000.  You're going to put in at the TO Bridge for the Middle.  When you're heading up the hill, watch for the "Snow Gates", and you'll make a left onto a dirt road, and then bear to the right.  You'll see the river and the bridge.

When you put on at this bridge, you'll have more than a 1,000, since it's above the diversion.  Looks like some conitnuous class III for a 1/4 mile, and then you hit the diversion.  Below there I don't know, never done that stretch.

 

If you're coming from Whistler area (beautiful drive, do it in the daylight), then you can eyeball the upper upper stretches, and see if there's anything that "fits the bill".  There a few cmpgrds, and informal sites in this stretch.

 

Another option in that area, though it may be high, is the Lower Stein.  You hike up 2 - 3 miles on a trail on river right.  Some good continuous boating, depending on flows.  Take a ferry out of Lyton.

 

If you're in the Pemberton area, there's also a Class III stretch on the Birkenhead, goes from the first bridge upstream to just below Owl Creek Cmpgrd (good place to stay).  Upper Birk (Class IV - V) will be high.