approaching Leadville from the south on those hiways is the least steep. you stick mostly to the valleys, although surrounded by 12-14,000 ft mountains.
from I-25 to Buena Vista you go from 6,000 ft to 8,000 ft, but that's spread over 120 miles, some up, some down. The final climb from Buena Vista (8000 ft) to Leadville (10,000 ft) is spread over 30 miles of mostly straight roadways, so no sharp curves or white knuckle drop offs.
Its mainly when you take E-W routes through the Rockies that you do a lot of steep up/down.