I have an auto (4L60e) in my LSx S30, but I never really considered a manual tranny as an option. I have several reasons, mainly due to the fact that my left knee has been replaced so when its cold out I couldn't imagine having to push a clutch pedal.
Also I like the simple ease of having an automatic. They are consistent and nice for just cruising and not having to worry about having to shift, especially in stop and go traffic.
Lastly I enjoy drag racing from time to time, its a fact that auto can 60' better than manuals, plain and simple.
Don't get me wrong manuals are fun too, but my dad has always had a saying since the 70's: "Manuals are for impressing High School kids, automatics are for winning races."