Good postulating, Havok, and I totally agree with you about the men's side... it's really hard to see anyone beating either Rog or Rafa, especially since Federer beat Nalbandian last week and he's always given him a ton of trouble (for the record, Nalbandian still holds like a 6-5 lifetime edge over "old Rog").
The women's side is way more open, but for the first time ever, it's REALLY tough to pick against Petrova. She's never been one of my favorites, but she's beaten all the big players on clay this year, with the exception of Kim (who should do well, but not enough to win, I don't think... too bad, too...) and she's also a two-time Roland Garros semifinalist, too. If she's gonna win one, it's gonna be this one. She's got the pedigree, she's on fire, and of all the Russian girls (excluding Sharapova) she's really improved her mental stability (though 7 titles in the past 7 months does a lot to improve that, too).
Also, don't quote me, but I seem to recall reading that Lindsay was most likely not going to play Roland this year and concentrate more on Wimbledon. I could definitely be wrong, but I won't be surprised if she doesn't show up. Davenport on clay = clumsy clumsy. And I like her, too, but she won't win, sorry. Kim won't let her beat her again if they meet, and Pierce or Sharapova or Mauresmo or Petrova or Dementieva or any number of other quality clay-courters would be able to fell the giantess.
As for Mauresmo, as if her expectations from the French crowd weren't enough already! Now she's got the "defending Grand Slam champion" label on her head, to boot! I'm just musing, but I think she's gonna make a LOT of French people unhappy (again) when she goes out well before her ability level should take her... shades of Ivanovic last year, maybe.
So what am I saying? Haha, no idea, it's such a tossup, but I still think Nadia's got the game and the right lead-up. We'll see how she does in Rome this week, but she's my pick. Also, look for Hingis to outperform a large percentage of the field; she's been impressive so far (not counting the Williams match). I'd say back-to-back Grand Slam quarterfinals might be in order!
Wow, I can be so boring. Hope this is well received!