Mania sold out within hours of tickets going on sale: that was some seven months before the show was scheduled. Mania sells itself. People don't order Wrestlemania because of who's going to be there: they order Wrestlemania because it's Wrestlemania. If anything, WWE sometimes goes out of their way to make Mania less watchable.
Cena should not have won the Rumble under any circumstances. Especially since they already knew a year ago that they wanted to do the rematch with Rock. They should have given the Rumble win to whomever is going to challenge for the WHC. Orton and Jericho are equally bad choices: not only does neither one of them need it, but Jericho is only signed through to Mania, and is likely going back on tour with his little rock band shortly after that.
The reason Miz's push bombed was incompetent booking. His relative stature had nothing to do with it. In fact, a big part of why it bombed was because they waited too long: midway through 2010, Miz was one of the two or three most over guys in the business but, not only did they not pull the trigger then, they then spent the next six months making Miz stop doing everything that got him over in the first place. And, by the time they finally gave him the belt, the fans had moved on.
If you don't think that Bryan is over, you're insane: Bryan was over the day he showed up on NXT. He was the most over from the Nexus angle, and he was still the most over when he was rehired after Mattel pulled their hissy fit. He managed to turn the utter embarrassment of being humiliated by a curtain-jerking WHC loss at last year's Mania into becoming one of the most over guys on the roster. He's like Chris Benoit, with triple the charisma, and none of the psychoses. And, by the way, when the crowd is screaming for you to put a guy on, like they have been with Bryan, it's not force-feeding.
And much of the same holds true for Cesaro: this is a guy who has been booked strong against everybody he's been in the ring with, even in losses, has had very good-to-great matches with everybody he's been in the ring with (he's been in the ring with Khali twice, and dragged him to two of the five best matches in his career!), and gets great crowd reactions whenever he comes out.
Not only do I not agree that Cesaro isn't ready, I'm more worried that WWE is going to wait too long to pull the trigger on him (just like they did with Miz, as I stated above, just like they did with Jericho, over a decade ago, who should have gone over Triple H on Raw in 2000, just like they did with Kofi Kingston, who was WHITE HOT coming off of the feud with Orton in '09, just like they did with Barrett, who should have gotten a run at Summerslam '10). And that, by the time they do give him a run, that WWE will have gone out of their way to water down everything that makes Cesaro great.