So, you are correct in some ways, the saunas in Colombia are not really about hiring, although some of them have guys for massage that can be contacted reasonably quickly. The saunas in Colombia are busier socially and in line with Brazil around the end of the working day. I've always enjoyed the saunas in Medellin but its a very different vibe from say 117 or 202 in Rio. In respect to your type, again not necessarily so easy in Colombia, in general the men are less tall than in Brazil average in Colombia is around 177cm but they are well endowed so that shouldn't be a problem.
If you are around Poblado and go on Grindr or Scruff there will be some guys who are available for hire, and will often message with their services.
Bogota the same, but you do have as you mentioned the St Moritz option, but the last few times I was there, the guys were definitely more twinkish.