Last night I went to a large social event for Jewish grad students and young professionals in my town. It was a lot of fun. I had a good time and met some cool people. I didn't bust the bank on the bar crawl (only did one drink per bar rather than the two or three many others were). I was not as worried about that as transportation.
Like many cities, Denver has fair public transportation, but not at night. The area of town I was in is not near our light rail, so I was pretty much stuck with either a DD or cab. I tried to plan it out with a friend to leave a car off, take a cab home, and drop off in the morning. It is not a wonderful part of town so neither of us wanted to leave a car.
Fortunately, my roommate was a nice guy and offered to drop us off (using my car, as he does not have one). That covered one way of the possible cab fare. I banked on us meeting someone nice who didn't mind going 10 minutes out of the way to give us a ride back to my place. I figured, worst comes to worst, we split the $10 or $15 for cab fare home.
Fortunately I made a couple of friends at bar 3 and took a ride home after bar 4. I could have stayed out longer, but the ride got us home at midnight. I don't mind being home by 12, so it worked out great. I also made hopeful good friends out of it, so it was a good, frugal-ish night out at the bars. Bars can never be totally frugal, but you can work it out right to cut costs by asking for the drink specials and avoiding cabs.