Drag Curls are a fine biceps exercise. Bend the knees slightly and keep the bar touching the body (elbows straight back, never flaring out) throughout the movement. Hence the name Drag Curl. You can go just about as high as the lower pecs. The contraction is very strong at that point. Of course it would be impossible to go all the way up to the neck area from that curling position.
Might also investigate the one arm Olympic BB curl. First choice over a exercise bar because it is longer and that much harder to handle. Going to call upon supporting arm and forearm muscles not usually recruited by normal curling exercise. Try it and see for yourself. Cable curls may be a close second in this regard. I loved these things in my younger day when first starting lifting with serious intent.
Some other suggestions to relieve boredom when curling: Consider the Reverse BB Curl, as another forgotten bicep exercise that few BB'ers do now a days. Some may think it is only a forearm exercise but it can be an excellent bicep builder. Try a false grip (thumbs over the bar) from time to time for a different slant to the Reverse Curl. Keep the elbows glued to the sides throughout.
And Also: 1)Sit on the end of a bench (elbows resting on the end of the bench) and curl a BB up (applied to a DB also) from that position. That close grip and angle of the arms should give a very strong feel to the biceps themselves. 2)Try curling a BB when on an Incline bench. Bar resting on the mid thighs to start. At the top/finish position lift the elbows up as high as you can and contract/flex the biceps strongly for a second or so. Lower and repeat from the bottom position. 3)Can also do DB Incline curls, with the DB's hanging all the way down to the sides of the bench. A prime mass builder. 4)Sit on a bench, BB resting on the lap, and do curls that way. A little more than a half way curl but a very effective movement.
Than there are Cheating curls, a true mass builder when done right. The point being, that every rep from start to finish is done in a cheating style. Not just the last few reps of a heavy set, but every rep. But never take that exercise to the point where you are doing reverse cleans. With a cheating style you are in complete control (or should be) of the movement from start to finish. A lot of guy's fail to understand that and allow too much weight to be used. Really defeating the whole purpose of the cheat curl. It is a form of the overload system.
To me, there is nothing more boring and a waste of time than doing any form of direct bicep or tricep exercise. For anyone else, than great and good for them if they need (or think they need) bicep/triceps exercises. I have not done direct arm work in years. No big deal, just my feelings. Good Luck.