I'm against voting for players, since the fewer popup voting things the better. Also everyone would rate me 1 but IT'S NOT LIKE I CARE.
Regarding Hightower, a single round would be great, OR a time limit that fohirces it to end. The other night was, if I recall correctly, 30-40 minutes with a single round, so it's not like a single round will fix it. If teams are unbalanced, both rounds in hightower can go really quick, on the other hand.
I don't think playing it every X hours will help either, unless X is say, 48 hours. Because if the server is busy only at 9 EST, and people only vote for hightower at 9 EST, it's going to always be available even if it had an 8-hour cooldown.
What I have always campaigned for is some genius to edit the map and add the option that makes the carts move themselves once a certain amount of time has elapsed. Of course, this would still presumably result in a tie because of the two places where the carts roll/fall back, but one team might jump on the cart to prevent a tie.