I think I'd want it on Summoner's Rift or possibly even on Twisted Treeline, but with some serious changes to make it more exciting. Built-in, long-range but limited mobility for defending against stolen flags (think Tport pads in nexus siege), and maybe holding a flag drastically lowers your resistances but gives an active speed/mobility boost of some kind. Stuff to ratchet up the intensity in those chase moments and alter the balance of power.
I don't think keeping towers the same as a normal game would be terribly interesting - if you're just trying to push lanes to reach inhibs, the game is essentially not much different from standard league. But if the towers (and maybe jungle, to some extent) get some alterations to support more of an infiltration and chase kind of gameplay, it could be very cool.