We are getting married at El Dorado Maroma near Playa del Carmen in March 2010. It's all inclusive and adults only. You may be able to get rooms there for under $2k - just check with a travel agent. There are a few El Dorado resorts (all adults only) that are all inclusive. Some have more activities and ammenities than others. El Dorado Maroma is smaller (which is what we wanted). They also have Azul resorts that are family friendly, but I think you said you didn't care about that.
Anyway, I hope this helps!
Happy Planning!