Best Carb Sources for Sustained Energy During Heavy Lifting

I have been feeling a bit flat during my heavy leg sessions lately. I think I need to look at my carb sources. I usually eat a lot of white pasta and white rice because they are easy to digest, but maybe I need something more complex?

I am looking for the best carb sources that will give me sustained energy for a two hour workout. I have heard good things about sweet potatoes and oats, but they are so filling. I find it hard to eat enough of them to hit my targets.

What do you guys eat in the hours leading up to a big session? Do you find that specific carbs make a difference in your pumps and strength? I am really trying to push my numbers on the bench and squat this month and I do not want my nutrition to be the weak link.