springs

I want to get a brand new set of shocks for my LTZ tahoe2007, and was thinking about a set of blistein shocks, does anyone know of a really good comfortable ride, set of shocks to go with for these SUV's? Reason i was thinking about blistein's, is because i have them on my chevy trailblazer also...

When should I replace my springs and shocks. I don't hear any popping noises when I hit bumps or pot holes but it seems like a much rougher ride than usual. Current mileage is approx. 90,000.