Re: WOW for someone who prefers to play solo.
Prot, specced right can be good for groups of mobs because of the damage shield.
Anyway, I can't believe you had a hard time at 50, at 50 there is so much more to do than at 30-49 it's crazy. You got past the hard part, which is late 40's.
At 50, you can do to Ungoro, Felwood, Eastern/Western Plaguelands. There's a level 50 class quest in Azshara (find in home city) for each class, that has several quests that are solo to start.
In the early 50's you can hit Winterspring and late 50's you can hit (58) Outland. You can do 50-58 so fast and hit Outlands it's not even funny.