Yeah the brooklin buildings are great, they do not fit a Vegas Style theme though, they could be used for quite a few American cities but I would say older cities and ones more north/east coast, it wouldnt really fit LA/Vegas most of the south west cities tend to favour a similar build style. To be honest, I might rezone a lot of my HD resi to low density. Honestly looking at google maps, if you exclude the strip, Vegas is basically all low density houses in big squares, a lot of other south west cities, Mirimar/San diego/the vast majority of Los Angeles all follow the same style.
I am going to abandon the theme manager idea also for my city, there just are not enough assets that fit my theme that will work with it, but I dont think it will be too much to place the apartments manually, then zone the low stuff, everything in the strip needs to be manually placed anyway due to the way the assets are and how built up the immediate area around the strip is.
I know I said it previously, but I had a very good trawl through the workshop this morning, and there are absolutely tons of UK assets, vast majority of which are also growables, I would totally make a UK style map if I were to start a new one today.