One nice thing about the prot pally is he can heal and cleanse himself. Also hand of freedom is great. If you boost the instances that are normally used, SFK->SM->Strat having the pally is really nice. I have boosted with a blood dk and it made SFK and SM really fast. So fast I was always hitting the instance limit which gave me time to learn new skills or hearth and get my mounts and what not. With the pally it was a little slower but it was well paced so I never really hit the limit.

In Strat I could pull whole sections with my pally. I had to make smaller pulls with my DK but it still felt faster.

Edit: i just favor my pally a little more cuz he is a one stop shop and feels a little more controlled. Heal, rez, bubbles.