Went to Chicago for 36 hours last weekend.
Besides a short trip in my car I used mass transit to get to and from my friend's wedding.
Here's the breakdown:
1) Drive to the Table Mesa Park and ride. Cost to leave car 48 hours > $2.00
2) Bus ride to downtown Denver on BX bus: free using Eco-pass (I worked for a few hours at my desk)
3) Bus ride to Denver International Airport (DIA) using the AF line: free using Eco-pass
4) Southwest flight from Denver airport to Midway airport: $219.xx
5) Bus ride on the 55 Garfield route close to my parent's apartment: $2.25 but only had $3.00 so paid $3.00 since no change given.
6) Walked to my parent's place. About 2 blocks from the bus stop.
7) First night of sleeping: free
8) Bus ride to train station in the afternoon: $2.25
9) Train ride using the red and brown line: bought a $5.00 transit card before getting on the train.
10) Time at wedding. Fun!
11) Return on bus line around midnight: free since part part of $5.00 transit card purchased earlier.
12) Bus ride on 55 Garfield line: also free since part of transfer using $5.00 transit card used earlier
13) Slept second night at parent's house: free
14) Bus ride using the 55 Garfield to airport: $2.25
15) Southwest flight back to Denver: part of airfare stated above
16) Bus ride back to park-n-ride where I had my car: free using Eco-pass card
Cost of using public parking and public transportation: less than $20.00 for a day and a half in the city.
Total cost of transportation: ~$232.00
I'd say using mass transit with a commuter card and transfers saved me quite a bit of money. If I had taken a taxi to the wedding it would have easily cost $60.00 to $80.00 dollars both ways.