Build something that works
google forms is good as well
If your purpose is just to build a landing page, you may not need to do this from scratch in Rails. There's a lot of great landing page builders like lauchrock.com or unbounce.com. They offer drag and drop design solutions with an email database when people sign up on your landing page.
If you're going to build it on Rails, try looking at wufoo.com. You build the form on their actual site, and then they generate the code that you paste into your HTML file where you want it embedded.