I've always been baffled by wedding anniversaries, to my mind it is something personal and private between the two of you. I just don't really understand why we receive cards from friends and family on our anniversary.
Having said that, I do like a good party!!! For significant anniversaries, 25, 40, 50yrs etc it is nice to reunite your guests, bridesmaids, best man and all have a good laugh at what you were all wearing and reminisce.
Ultimately it is your choice whether or not you have a party. A summer bash might be nice if you feel inclined. Equally the two of you could just take yourselves away for a night/weekend/week and enjoy some time together.