There are several buses that go to Colorado Springs leaving from Greyhound terminal, Union Station and the airport in Denver. Many of the bus companies run tour buses to sites in colorado springs. You have to call around and see. In good weather, you can ride a bike out to Garden of the Gods. Me, I have always drove.
Frex busses are the easiest, then you can take local springs busses from there- google the routes and times for both of them. otherwise drive i-25.
If you re going to hang out in the Springs, fly into Colorado Springs airport instead of Denver. It will probably be cheaper
It s just about an hour drive south on I-25 to get to Colorado Springs, very simple.
Front Range Express, the website is pretty easy to follow.http://www.frontrangeexpress.com/