How good of skier are you?
I'm in WI also here. If your a solid skier (7+) I'd recommend going with some with something like the Watea 78, Head IM 77 or 78's, Dynastar Legend 8000, or HotRod Nitrous, they will handle the conditions in WI, UP, and your trip out west. Watea has a twin tip though its not really design for the park but will hold its own for your few runs through the park each time out.
Volkl AC Motion, Fisher RX Red Heat, Head iSupershape Magnum and Atomic Metron 9's are also nice midwest skis. But these are more design as a groomer only skis but can handle the off trail stuff you find around the midwest.
Otherwise your pretty much looking at a getting a true carver ski and then rent when you go out west. Which does great for are conditions.
There is just so many choices and in the midwest here we usually don't have the luxury of Demo Days at the hills to try skis out. Read reviews and read some more reviews. Should beable to at least narrow it down to a three skis or so.
Good luck in your search. I'd lean more to the first few choices if you like to hit up Mt. Bohemia or do some of the Porkies Snowcat skiing.
P.S.: Talked to guy last season skiing on some Head Olson Pro's and he was shredding the whole hill without a problem. I'd say he was a solid 8 to 8.5 skier. He really said he bought them more for the park then anything but after taking a few runs he has never gone back to his other ski. But expect to pay more in that $400 to $450 range for them.