Viewing pdfs with vim latex-suite: !start Preview shell returned 127

You can use !open -a Preview to open Preview.

Here is my settings to make <leader>lv work for me:

let g:tex_flavor='latex'
let g:Tex_TreatMacViewerAsUNIX = 1
let g:Tex_ExecuteUNIXViewerInForeground = 1
let g:Tex_ViewRule_ps = 'open -a Skim'
let g:Tex_ViewRule_pdf = 'open -a /Applications/Skim.app'
let g:Tex_ViewRule_dvi = 'open -a /Applications/texniscope.app'

Note that I am using Skim instead of Preview as PDF viewer here. You can simply put:

let g:Tex_ViewRule_ps = 'open -a Preview'
let g:Tex_ViewRule_pdf = 'open -a Preview'

to view the resulting postscript or PDF file with Preview.