I would not take Mauer with my first pick. I would personally rank your available options:
1-5 as you mentioned
Those big bats give you a nice foundation for average AND power, and they have a much higher chance of staying healthy and repeating last year's production - two things Mauer doesn't have going for him. If you really want him, take him if he's available with your 2nd rounder, but please take the big bat with your first pick. The guys listed 6-9 are pretty interchangeable - some have Kemp at 6, others have Teix swapped with Cabrera - whatever you choose is fine, but these are my rankings for this group of players.
Notice how I only listed enough players to get to spot #12. After this, opinions vary widely. Some would say Lincecum or Halladay, others would go for Tulowitzki, J. Upton, Holliday, etc. I would personally take the best hitting numbers at that spot, regardless of position. If nobody from the list I made at the top fall to you at #13, I would personally go Holliday/Tulo, but it's personal preference at this point. Hope that helped!
If you don't mind, can you help me with my post? http://www.fantasybaseballcafe.com/forums/viewtopic.php?t=403675