Well before I begin my answer I just want to open with this is who I would LIKE to see (as you asked), not necessarily what I feel will be the case. We'll start bottom up I guess.
DIVAS- Beth Phoenix. I know a lot of people will go with Kharma on this one, but I'm just trying to think ahead. Even though everyone with half a brain knows Kharma is capable of dominating the Diva's division, WWE will still probably want to set-up jobbing matches/beat downs prior to Kharma going right for the belt. While this is going on, WWE can have Beth beat Layla for the Diva's title, setting her back up as a "dominant" force. Then, the two forces, Kharma and Beth, will be able to collide for the title.
Tag Titles- I agree with the OP, it has to be PTP. They may not be completely over with the crowd yet, but I think it is only a matter of time and quite frankly I like them a lot, especially with AW as a mic piece. Ive always liked Darren Young's look going back to NXT Season1.
US Title- Drew McIntyre. This one epitomizes why I put in that beginning notice saying this is what I would LIKE. I feel that it will give back any credibility the title may have lost around Santino's waist, plus I feel like it is a good way to get Drew back into the midcard, someone who I feel is very talented (I discussed this in a previous post, so I won't go detailed in)
IC Title- Alberto Del Rio. Damien Sandow is a very close second. After MITB, Del Rio will be without a feud and I'm sorry but Rey vs Del Rio has never done it for me and will never do it for me. The only benefit I see out of Rey is if Del Rio gets the best out of the feud and comes out a more over, "evil" heel. I think Del Rio and Christian would be able to put on some spectacular matches and the IC title will become part of a feud between two proven main eventers. I could see Del Rio becoming a dominant champ, eventually losing it, and bursting back into the World Title picture.
WHC- Randy Orton. I'm dying to see heel Orton again. I used to mark-out every RKO and punt. My answer of Orton as the next champion is almost solely personal. Plus, I know I am not the only one that has grown tired of seeing face Orton. Even Randy wants heel Randy! Attack Sheamus from behind when he returns from suspension, and a match at Summerslam is set-up easy enough. The only creative issue with this is Wade Barrett, who is ready to return. You could throw him into the WHC match at Summerslam and make it a triple-threat, I wouldn't mind seeing him win the title as well. He was choice 1b for this answer.
WWE- John Cena. If the rumored feud between Punk and Cena comes to fruition and they do have a match at Summerslam, I would not want the change to occur then. If WWE is serious about Punk as the Macho Man to Cena's Hogan, Punk should beat Cena at the second biggest stage WWE has to offer. Yes, Punk won at MITB, but since then Punk has gotten even bigger and let's not forget that the match wasn't completely clean. There is no reason that WWE Creative won't be able to come-up with another reason for a Cena/Punk match at one of the fall PPVs; that is when I would have Cena take the title off of Punk. While I would like Bryan as well, I can't see that happening at MITB but you never know. That AJ chick is pretty crazy