The first step to having an amazing wedding is letting all your guests know about it!
If you are planning an out-of-town wedding or have a lot of guests (let's say 25%) coming from more than an hour away, save the dates are a great thing! They are a way of letting your guests know some of the basic details of the wedding. Most of the time, they feature your engagement photos and the date and basic location (city and state) of the wedding. They can be as fancy or simple as you want them. You might design a rustic themed Save The Date and then change the theme of the wedding. These are just an FYI for the guests. Don't focus too much on "matching" them to the wedding.
INVITATIONS ON THE OTHER HAND--
Your wedding invitation will set the tone for the wedding. Generally, they either match the theme or colors of the wedding. They have all the important information for the wedding and reception.
Your wedding invitation will be a sign for your guests. It will give them an idea of what the feel and theme of your wedding is going to be.
Personally, I LOVE when I get an invitation in the mail it is shows the wedding colors. It saves me the worry of matching the bridal party!
Professionally, I love when my brides choose a theme that shows off their personality and their theme. Carry through with your theme and give your guests a sneak peak into your wedding!
Make them fun, fancy or simple. The most important thing is to make sure that they have the information your guests will need. There are things that will help them know more about the wedding and reception such as times and locations.
Sometimes the main invitation will not have the space for the added information. Don't be afraid to have information cards with your invitations as well that include exact addresses for the venues, hotel accommodations, shuttle information, RSVP cards (there's going to be an entire post for these soon!), dress code, parking information and anything else you might think is important.