It depends what time of year you plan on going. I'm not sure I would want to venture into Denver and/or The Rockies in the coming months without proper winter setup. We were there in June 2017, and there were roads closed through Estes Park as they still had several feet of snow on them, and it was calling for snow that night again.
I will say, if you get the opportunity, go for a cruise through Rocky Mountain National Park. We met a friend down in Loveland, and then cruised up through the park, and went to his place south of Denver. It was like a 5 hour trip total, but it was absolutely stunning. It was hititng 85 degrees at the based of the mountain, and was 35 up at the peak.
Back on topic, the Vibe handles fine in the elevation, even with a trailer behind it. Biggest thing would be the snow if you're venturing up there this time of year. I'd worry about tires, and changing all fluids. We added a trans cooler, since I was towing. Also replaced all fluids, coolant, engine oil, power steering, trans fluid, brake fluid. etc. We did a nearly 10k mile trip from PA, to Mount Rushmore, to Rockies, to Grand Canyon, to White Sands, and back to PA. Car handled it absolutely flawlessly and I still wouldn't hesitate doing it again now that she's at 200k miles.
