Thank you notes are an absolute MUST to show your gratitude for the outpouring of love you experienced during your wedding. While e-mail, texting, website and Facebook posts are appropriate for some things...they most certainly do not replace the kind gesture of a hand written note and should not replace your wedding thank you cards.
Some people will tell you that you have a grace period of a year to write your thank yous after the wedding, but why leave it hanging over your head for that long?? Our goal was to have them done as quickly as possible after we returned home from our wedding. We are now 6 weeks post wedding and just have a few left to write for gifts we recently received.
As for the style of your thank you cards, that is personal preference. You can have cards printed before your wedding with your new name on them, but we opted to share a wedding photo on ours. Polka Dot Papers, who did our wedding invitations, offered to do a photo card for us. One of my bridesmaids had these made by Grey Ink a few years ago and I loved the card and still have it on my refrigerator! When we returned from our honeymoon I sent her a photo and she had the cards to us within a few days. In the mean time we made sure we had recorded all the gifts given to us so we did not leave anyone out.
To make the card writing more fun, we cooked dinner a few evenings and made a date night out of it. Brandon wrote the cards to his friends and family and I did to mine. The wording does not have to be anything profound...just thank them for taking the time to come to the wedding (if they did) and how much their love and support means to you. If a monetary gift was given, you don't have to mention the amount, just that you appreciate their generosity and how much it will help as newlyweds.
In the end, it is the act of taking the time to write the note that matters most.