Does one invite adviser / cohort / lab to one's wedding?
Just invite the people you would like to have come.  If there are other students, post-docs, faculty, or staff that you are close enough to that you would want to have them at your wedding, then just invite them.  There is no established protocol for who you should invite, and no one is likely to be offended if you invite some of your lab-mates but not all of them.

This is, fundamentally, a workplace issue, rather than an academia issue, although the laboratory workplace for a graduate student poses some unique challenges.  Whether to invite your advisor is just a particular example of whether to invite your boss to the wedding.

I got married halfway through my Ph.D., and I invited a few other graduate students.  I did not invite my advisor, and I know that he was not offended.  When I got back from my honeymoon, he even gave me a small wedding present.