i've got We Rule Gold on both devices (iPhone 3G on iOS 4.x and iPad), but iOS 4 really bogged it down on my iPhone so i zapped it from my iPhone and kept it on my iPad. but the iPad stays home, so i can only plant crops that i think i can harvest once a day instead of several times a day like i used to.
UniWar i play on both devices, whichever one is in front of me at the time. it's a low res game so i keep it in 1x when i play on the iPad.
there aren't any high res games on the iPad worth playing so far. an iPad game would have to be a really really deep game with high res that would get me to pay 4.99+. Myst has awesome high res pix.
i might get that one. i never did finish it on the PC.
how about AOE or Starcraft on the iPad?!?! now that would be tempting. not enough horsepower? too bad.