As far as an "ease of use spec" for a DK multi-box tank, I've found that THIS is a very friendly spec. The single target threat is quite good, and it does not suffer in the AoE threat department either. I've respec'ed my DK over 35 times and have tried just about every combination you can imagine. This spec is very solid and also extremely flexible. Glyphing properly and using a good rotation is key however. The rotations can be complicated, but I can give you those if you need.