R.,
I just attended a wedding that fits your situation, however, they were not married before the wedding. (had their child and were living together, homeowners, and and the works for two years before the wedding this summer.) Everything else, just not married yet.
They did the "full-package" so to speak. Invitations, RSVPs, bridesmaids, groomsmen, their son was the ring bearer, in our church with our pastor, formal reception afterwards, dinner, cake, and so on,heck they even had a bridal shower and bachelor party even.
I guess what I am saying is: whatever you feel comfortable doing go ahead and do. Do what you feel is appropriate for your situation. (Remember, if you feel something may not be appropriate to do, then it probably is not and you should reconsider that idea.)
The "cons" I heard guests speaking about— 1) it was uncomfortable for a lot of folks to expect gifts from them when they had basically been married for a few years prior.
2) Other women were commenting that it was inappropriate for the bride to be wearing white.
Other than the cons I have mentioned everyone seemed to really enjoy the special occasion and wished them their best.