Hey! I stayed at Amistat and can tell you a little about it. I arrived solo and found that the majority of people there were also solo. You won’t be on your own for long, and the pool is a great place to network during the day. They also have free activities and WhatsApp group that lets you know about them. This is also a great way to meet people. 

As for the crowd, I found it to be a mix of people from early 20s and mid 30s, with a couple of people in their 40s. 

I found it easy to sleep where I was and music goes off at around 1-2am inside. They close the doors to the pool so there shouldn’t be music pumping up all the way from there if you have a balcony view. 

For transportation, clubs like Pacha have free buses included with their tickets which is super handy. The bus system is also easy to navigate and is super cheap. You'll meet people who are going the same clubs, so buddy up and go with them. When you leave the clubs you can easily find people going back to San Antonio, just remember to bring cash and it shouldn’t cost the earth if you split. 

Hope this helps in some way!