I didn't bother to do a wedding website. To me, it was wasted money. However, I already have hosting space, so I could have just registered a domain name and forwarded to one of my exisiting hosting sites.
However, I think a smart idea would be to pick a non wedding name. Like jackandjill.com as opposed to jackandjillswedding.com. Or thesmiths.com. That way you can still the domain after the wedding for a post-wedding site. You could continue it as a "family website." Blogs, pictures of you, your pets. If you have kids you can put a section which focuses on that aspect of your life, etc. Also, if you guys have family parties (ie at christmas, thanksgiving, etc.) you can include all that info on your site as well.