The best champs to go bottom are those that can be relatively hard to gank or are overall good at defending themselves, but are very good at exerting lots of pressure on a lane at the same time.
Right now I think the 3 best bot picks are Soraka taking the crown, then Yorick, then Urgot. All of them are very hard to kill but put on **** loads of pressure. Others like Cassiopeia and Malzahar can bot extremely well, though I don't think they are as strong as the others I mentioned. Although they still are extremely strong picks when they are not bot.
I find that having multiple forms of hard cc goes a LOOOOOOOOOOOOOOOOOOOOONG way too. Champs that can bring burst along with awesome cc are extremely valuable for roaming, like LeBlanc, Ahri, Ryze, and Kassadin.
Poke is also very valuable at making point defenders more vulnerable and less risky to dive and take down. Champs like Kennen and Ezreal are especially great to have.
Mobility is another thing. Panth's ult for example can make the difference between winning or losing because he can get back to a point so quickly after he rez's.
Really though there is not a single one strategy that is especially dominant as far as line-up, but I find a team that has a combination of those things tend to do extremely well in Dominion. Very few champs are outclassed as Dominion really brings out the best parts of each characters kit, and those champs are generally seen as up all around (Nunu, Mundo, and Vlad being the key offenders really), but even they have SOMETHING to offer a line-up.
I typically plan with my team to run 2 top, 2 roam, 1 bot.