If Vesley is there at #12 it is a no brainer to take him, but with the #5-#6 I would say no. Vesley has continually been put in in the top five for a lot of mock drafts so yea if he is available at #12 I think you would have to take him.
Smack has moved up to #7 in Draft Express's Mock Draft and in ESPN's Lottery Mock Draft Simulator the default picks have him at #7. I am definitely on board with taking Smack with the #5 pick, unless we can get Irving or Williams I want Biyombo.
Regarding the #12 pick, I really have nobody who I really want yet. The obvious pick would be Jimmer, but I say no no no. Someone like Kawhi Leonard or Alec Burks would be great choices for the Jazz at #12. Actually now that I think about it my preferences assuming the Jazz don't move up are Bismack Biyombo at #5 and Kawhi Leonard/Alec Burks at #12.