Welcome to the community mtrummel and thanks for the post!
I wrote an article regarding this and you can find it here:
http://www.greenhybrid.com/learn/art...fficiency.html
In there I mention a certan amount of "bars" of assist while accellerating. Since I wrote that I've found out that the slower acceleration as practical you can do will provide the best economy.
For example when accelerating from a stop I "surf" the edge of assist to just
barely keep it on. Traffic permitting I'll cut the assist at 30-35MPH and dramatically raise (Lean burn). If on a level surface it's usually raised to about 60MPG and accelerate from there. That's if accelerating up to a 45MPH limit.
You'd be suprised how often you can accelerate at a very slow rate, even in traffic. Keep an eye out behind you. If your follower is WAY behind you can back off and save.
If I'm getting onto the freeway or any other fast pace I'll maximize and use any downhill portion of the road to gain speed and take it from there.
Using the same techniques in that article we also raised our Grand Caravan from 15-16MPG up to low 20's. The highest I'd been able to raise the Grand Caravan economy so far was 28MPG.
VERY careful driving but look at the results.