one day at kings dominion is definitely enough. my wife and i usually go once a year but we just drive there, it's like 90 minutes or so away.
we always go like early june before schools get out, on like a tuesday. we usually get there right when they open and are ready to leave by like 6pm or so and have gone on everything we have wanted to, which usually includes every roller coaster, the white water canyon and log flume, and then all of the stuff in the water park. have to hit up the lazy river a few times while there! and also other random rides we want to go on.
gameplan wise, i'd recommend when you get in, kind of make a "circle" around the park, going to the left side first where the berserker ride is (the pirate ship that flips upside down). then you can kind of hit up all of the rides making a circle this way, and then after that go on the water rides like log flume, white water canyon, that are over on the right side of the park. then after all that, go to the water park. that's our typical path and it works out well, and then when we're done with the water park we're just ready to grab some food then leave.
we sit in the front of all roller coasters too. usually the longest wait is like 15 minutes for the front. most of them, you have like 2-3 groups infront of you before you go.
i've been there in the middle of the summer on a weekend, and that is a time i would not recommend. it's been probably 7 years since i've done that, but i remember waiting in lines for like 45 minutes to an hour, if not more. just not worth it to me. if you can swing going during the week in the middle of summer, i'd recommend that over the weekend for sure.
as far as hotels, i'm not sure exactly but it's right off 95. i'd just go somehwere that is cheap and not more than like 10 minutes away or so. parking i believe is like $10 or $15 at KD too.