Britchick, it really is up to the couple. I've seen any number of renewals, and usually it's the couple walking down the aisle together, or just "appearing" together. Depends on the setting.
Did you have an elaborate wedding? Perhaps you'd really like the beach? Renewing vows is often a focus on the committment and love that has kept you together and the promise of growing old together. A bit of a different focus for the marrying couple.
I've been to one where the bride actually wore her original wedding dress. As she put it, since her husband had "doubled his investment" :D she'd had to have some creative alterations done, but it was lovely. They had it in the original church and said the same vows.
Truly a matter of what appeals to you.