I live in South Central Kansas. Lantana usually grows as an annual here EXCEPT if it is grown on the south side of a structure as a foundation plant, then it grows as a perennial. I can't speak for any other place, but here in Kingman, KS lantana sprouts back from the stem if grown on the south side of a structure where it gets protection from the cold North wind. A friend of mine here in town gave me some Ham n' Eggs lantana rooting’s she was growing on the south side of her house. Her lantanas have been coming back from the dormant stems for the past six years. I tried them on the south side of my house last year, and they re-sprouted from the stems this year for me too. Of course, I did mulch mine. I also planted some on the south side of my garage. I am not going to mulch those this winter just to see if they still come back too. And again I need to emphasize, they are definitely re-sprouting from the stems and not from seed that has dropped to the ground from the previous year. Below is a link to a photo of the south side of my house. You can see the lantanas towards the back of the house. Last year I had them planted where the Weigelas are at now, underneath the lead glass window. These Weigelas are not doing very well right now in this 100+ degree heat, so I am considering moving the Weigelas and planting New Gold Lantanas in their place.
Thanks for your report, Mr. Kansas! I believe I said (I think) that L. camara may be perennial if mulched and protected. Ham n' Eggs is a very, very old cultivar which has escaped cultivation in many parts of the world; perhaps it's extra hardy. Good luck to you with your Lantana experiments, and again, thanks for your comment.