I never get bored of progressing and gearing up my characters from lvl 1 to whatever the max lvl this year is XX blah blah. In general, the whole game is repetitive, regardless. I mean, what do you do at end game?
You raid the same bosses over and over and over again, new mechanics are added, with minor, some times major tweaks to old ones, get gear, and eventually reach a point where the game is finished.
Now in retail wow, you have options. So if you hate the leveling grind, you can pay your way through it, which is stupid to me. I never will do that. But if you hate leveling so much to the point where you never want to do it again, you do have the option to pay for it. Makes wow seem much less of an rpg at that point though.
Also, different options for raiding. If you stink at raiding as i do, you have lfr, which is really easy raiding. And if you do not like raiding at all, you have the 5 mans and junk that come with every expansion. I am more on the casual dungeon crawler/casual pvper spectrum.
And in bc classic, you have the option to skip the overall leveling process on one toon, or if you really want to, pay for 7 straight accounts and use the boost on 7 separate toons.
Basically the gist of my post is that the whole game is repetitive. You have so many options as well to skip parts of the game as well, either through blizard, or through end game gold transactions with other players. Regardless, i find the leveling grind repetetive and full of hard work, but i also find it fun. End game raiding and pvp and whatever else i find just as repetitive as leveling is, and in some cases, just as boring. It is wow. The whole game is repetive.