Is your sites accessible when you type http://www.yourdomain.com or HTTP://WWW.YOURDOMAIN.COM?
A few years ago, I discovered that a large company displayed their web site address in capital letters in a TV ad. However when you typed that address into your browser, you received an error message.
The DNS for that domain was correct, however on the server, there was a special software which was used to match the correct domain name to the correct site (name-based virtual hosting).
The problem with that software was that it was case sensitive. While the webmaster had configured the domain in lowercase letters, he forgot to install it for uppercase letters as well.
Most virtual hosting programs are not case-sensitive and accept either form. However should be aware that there could be a potential problem and you would lose a lot of potential clients due to this glitch.
Some people have their caps-lock enabled at all times. You would lose out on those visitors if your virtual-host-software is case-sensitive.
One many of my web sites, I use some scripts which convert any user input into correctly capitalized sentences just to make reading the feedback messages easier.