Given the already existing mechanics...
Why not just press
Thanks a bit more often?
That is, if the answer/solution is good, helps, or gives indication to a solution the questioneer can work out himself, brings in another approach, or whatever the thread its own 'requirement' for 'justification' is...
By giving "rewards", i would already know that Don wins each and every time, since his posts usualy excel any other other answer given in the regarding threads.
While i would agree that answers/solutions of such quality should be rewarded, imho anything else than a 'thanks' might become dis-encouraging over time because of 'pressure' since not everyone can write in such matters and provide so many indepth knowledge by heart has Don, Aia, Scrutnizer, Neo, Wise, Rudic, Akshay, WhobblerXL, Ravinder, and few others i currently dont recall.
Challenge question, just for the discussion, and who is going to 'judge' all those posts, compare their value for/to the thread opener (how do you know how good the answers were for another person??), compare their quality versus all the other answers given?
And who is giving advice in how to increase the quality of the posts, to each member, without giving the 'feeling' one is back at school, wether one wants or not?
My 2 cents to this nice idea
EDIT:
Just saying this suggestion is time-intense, needs a volunteer who is capable, has the time, and is willing to do it.