Congrats :)
I am struggling with the same question.
I have 2 bars ready for my Susie when it arrives... 58cm bosco and 66cm bullmoose.
I think I will put the bullmoose on first and change to the bosco if I find the bullmoose uncomfortable for very long rides.
I also have a Ritchey P29-er with regular MTB riser bars, so that factors into how Susie will get used, ie, not planning to ride her so aggressively.
Whatever you choose, do share pictures and impressions.