These missions are one of those "well kept secrets". I had lived most of my life in San Antonio until 15 years ago when I moved to Dallas. Since then, I have returned to SA to "do" the missions since we never did while we lived there. Go figure.
Just FYI, (Texans know this, but it hasn't been mentioned in this thread) one of those missions is the Alamo!
Do, if you can, visit these sites and take your cameras. However, don't go to take pix on Sunday mornings, some of them are still parish churches!
Also, FYI, there are 3 missions on the USA side in El Paso, and I understand 2 or three more on the Mexican side.