Ey up Luke,
First things first - make sure the poster has all the correct information a person will need:
• Where is the event?
• What time?
• Is the Entrance Free? (big selling point!)
I don't like the first version at all, it's very plain and the text tracking is too wide ...use tracking sparingly :)
I do like the 2nd version - although I think it's rather 'posh' looking currently. To make it fit a vintage style you could switch to a more brown/dark red colour scheme, and add more of a handdrawn/textured look - or a pattern to the background.
When I think 'vintage amusement park'... I think Zoltar from the movie Big:
http://1.bp.blogspot.com/-uVCxBJi3Lrs/TZKQ9XzN44I/AAAAAAAAAWU/ZQi_SpF_Awo/s1600/Big+Poster.jpg
haha.
I would aim for a style more like this: http://tyen.org/?p=1031
Here is a list of tutorials that might be helpful or inspirational: http://t.co/cdVHdo2
I think number 3 >> http://psd.fanextra.com/tutorials/designing/design-a-retro-styled-poster/ << would be a good look for your project.
Hope that helps? lol - Good luck, let me know if you want an further critiques! haha
- Dave