What we did was we had the wedding invitation with the ceremony time and location on one card, then the reception card. Then we had the enclosures as one sheet - a regional map for reference since our guests are split between 3 cities, a street map with directions from the ceremony to the reception (less than two miles) that had the directions numbered so it matched the map that had a line drawn and numbers at each turn, and then the wedding website is listed and it tells you for more details about the wedding, local weather blah blah please check the site. That gives us the map in case someone doesn't want to get the maps online (which, frankly, is all I did) and it gave us a spot to list the wedding website (which does not have registry info visible).
Since we also have it set up to take RSVPs through the wedding website via a form mail that my friend wrote up for us, it's also listed on the RSVP card. We have an RSVP card and envelope, but people in our circle and in our extended families simply do not RSVP by mail. So at the bottom the card gives you name to RSVP to (MOB) and lists her phone number, email and the wedding website as alternative RSVP modes (we didn't call it RSVPs though since apparently many people in the US don't know what it means anymore, so "The courtesy of a response is requested" instead).