It looks like we are still mulling over five levels. My thoughts:
After some playing around I have grown to like
Turn Around Young Lemmings. It can be completed with only 1 lemming lost.
I think this solution is truly talisman-worthy.
All the Sixes has a really excessive number of skills for only 2/3 saved. If we do not plan to change the stats then I can see this level being removed. Earlier I suggested if we keep this level then to have 6 of each skill and 60/66 saved.
Reducing the builders to 1 in
It's the Price You Have to Pay in my opinion makes the level more interesting (and harder). However the change also eliminates solutions based on trapping the lemmings between the posts.
I like
The Gate Trap Lemmings. It is the only level that I would want to see added to what we have now.
I just don't like
Where Do You See Lemmings? Nothing specific, just not appealing to me.
With three of these five levels to be in the pack I would choose Turn Around Young Lemmings, It's the Price You Have to Pay, and The Gate Trap Lemmings (effectively swap out All the Sixes for The Gate Trap Lemmings). This really screams make a poll to select which levels make the final list of 150 levels.