I use Lazzari's Mesquite Chunk Wood Charcoal, and it is great. Although I can't find it for less that $20 for 40 pounds, but even then it is cheaper than Kingsford -- and better for many applications.
I did an over-nighter with it last night for the fist time and I admit I was a little nervous, but it went from 10:30 p.m. to 8 a.m. this morning before I had to add fuel. I found packing it very tightly into the fire ring on my WSM makes a difference in how quickly it burns...
*2 Weber Smokey Mountain 18.5 & 22.5 w/Stoker
*Pre-1979 22.5-inch Red Weber Kettle
*Pre-1979 18.5-inch Red Weber Kettle
*1993 & 1998 Weber Performers
*Grill Dome Kamado smoker 18-inch
*El Cheapo offset smoker (CharBroil)
*4X8-foot trailered Santa Maria Grill
*Coveting a Weber Ranch Kettle
*Yellow splash-proof Thermapen
*Member of PNWBA/KCBS/West Slope BBQ Association