I stick with the same lifts but always change up the rep range, volume, and intensity. I log my numbers and then compare power weeks to the next power week, volume week to the next volume week, and so on.
I do push/pull/legs. This week is high reps for three sets. Last week was low reps for 5 sets. Next week will be medium reps for 4 sets. Then about every 4 or 5 training cycles, I will throw in a shock week to screw with my body. I'll do low weight with very high volume in circuits. For example, I might do benchpress super-setted with pushups. Military press super-setted with DB flies. Dips super-setted with triceps extensions. I then take 3 or 4 days off to allow for CNS recovery, and then start the cycle over again.
This has been the most effective way for me to train. I hardly think it is the best, but it is pretty good.