I think that St. Louis #1 is the most interesting - probably because you can only see it by taking a tour so you will learn a lot about the people buried there. At Lafayette Cemetery, you can go in and walk around on your own (be sure to check their hours as they close early in the afternoon), but you will be basically just looking, not learning any history. I would go with #1 as it is the most famous and most interesting. You might be able to find some good discounts on Living Social or Groupon.
I would look into combination Garden District/cemetery tour done by Save Our Cemeteries. Gives a lot of details about the cemetery (who's buried there, why tombs above ground, etc.) and then walk around Garden District and see historic homes as well as those owned by celebrities like John Goodman, Sandra Bullock, Archie Manning, etc. Meet up on Washington Avenue near Commander's Palace, so maybe do lunch there and then walk few blocks to Magazine Street, where there are a lot of antique shops, boutiques, bars, restaurants and a fun way to see a different part of NOLA than the French Quarter.
As relates to just the cemeteries themselves, although both are interesting and notable in their own way, St. Louis Cemetery No. 1, which requires a guided tour, being older and populated with more notable tombs, is probably considered more historic and interesting; it's also the Easy Rider (film) cemetery.
Thanks for the information! I knew i could count on you all!