Hi James, You'll will probaby get many suggestions on this one. I use 50/50 because I'm used to it. I would suggest you click operating tips and modifications on the home page,then click on firing up your weber bullet and checkout "The Minion Method". Hope this helps you.
I'm with craig. Lump can be awesome, but cowboy lump generally is harder to maintain temps. And if it is an overnighter, the kingsford is just going to be easier.
I have been using cowboy for awhile and like it but I havent tried an overnight cook with it. I just found some royal oak lump but other than that cowboy is the only lump I have found where I live.