Geoff,
I just moved here from WI a little over a month ago. The only way to CC here with an out of state permit, is if you were a resident of that state in which you have a permit from, such as Utah, Michigan, Florida, and probably others.
I have yet to apply for my CC permit since I moved here. I just don't have the money to buy the permit. So instead, I've OCed everywhere I've gone since I got here.
You can CC or OC in your car without a permit. Without a permit, you can OC pretty much anywhere that Colorado laws would let you CC (if you had a valid permit). When storing the vehicle in your car, you can just store it in a locked compartment. I throw mine in the glove box and then lock it when I can't carry it (still loaded and in the OC holster).
Otherwise, these seem to be the only places off limits:
-Places prohibited by federal law
-K-12 school grounds (keep in mind the 1000 foot Federal gun free school zone law)
-Facilities with security personnel and electronic weapons screening devices permanently in place at every entrance
-Facilities with security personnel electronically screening (such as handheld devices)
-Facility of public transportation
-Chambers, galleries, or offices of the general assembly, or a building in which a legislative hearing or meeting is being or is to be conducted
-School, college, or university grounds (unless you have a valid CC permit)
-On a Snowmobile
-Prohibiting Private Businesses
-Denver (and Denver County), Arvada and Breckenridge prohibit open carry
Unlike Wisconsin, you can carry in bars and restaurants that serve alcohol (without having permission from the owner). I've carried in Rocky Mountain National Park quite a few times, even right next to a sheriff and park ranger who didn't say anything to me.
Here's a link that will provide you with pretty much everything you need to know:
http://webcache.googleusercontent.com/search?q=cache:nTpaSaUeDugJ:www.rmgo.org/faq/
Enjoy your trip!