So, why that big of wire? Just throw a 90 amp breaker in your main panel and run 2, 2, 2, 6 wire. That breaker protects the run and you can still use the 100A panel in your shop. You'll probably never use the full 100 Amps anyway so, you won't need to up size for the 150' run either. If you really want the full 100A service, simply up your wire by one size.
NEC changed their standard for de-rating the neutral a few years ago. Now you have to calculate the load on circuits with the neutral leg (120V in this case) as apposed to loads with 2 power legs (240V, with no neutral) so, I always run the same size wire. It's not that big of a cost until you get into 400A and bigger services.
Plus, you only bond your neutral to ground in your main panel, you don't bond it on sub panels, FYI.