you can really only have more variety with co2 if you have the lights that match it
personally, I don't really see the point in running co2 if you aren't going to have high lights as well, most of the low to medium light stuff grows fine without it
My set-up will be high light in a few weeks and even then I won't be running co2 right away, not until I see signs that I need it
sometimes, I think of co2 more as a supplement for most plants than as a necessity
plus, I'd be more worried about what would happen if you didn't use co2 correctly than I would be about the possible benefits (if that makes sense)
I'd say only do co2 if doing high lights