Some more playing around...

This lovely flower was taken using Macro Auto Mode
I spotted this hummer "in the wild" in Oregon - both birds taken at 1600 ISO

So far I can conclude
1600 ISO is good for web photo or simple snapshot 
800 ISO is fine for a 4 x 6 print
100-400 is what you need for up to an 8 x 10

Just like most cameras - good light is everything

Going to be a long day tomorrow including sleeping in the truck...