The most common benefits at Silver is free bags and free E+ seat selection at check-in. Don’t think upgrades are going to start raining on you. The Y and B-up fares on CPU-eligible flights require PN class to be available at booking for the instant upgrade. If it’s not, which is very common, you’ll go on a waitlist which is cleared by status. Buying a Y or a B fare hoping for PN upgrade space to show up as a Silver is probably throwing money out the window.