Heading to San Antonio for a long weekend, what to do while there?

You will not need to lood far. Get one of the hotels on the Riverwalk right in the middle of downdown. It is beautiful. The riverwalk has hotels, shopping and dining, and attractions. You can take a guided boat tour down the river through downtown. Also, the Alamo is right across from it in downtowm -the best museum to see. You can also drive through the country side. San Antonio is in the hill country. Also Austin is a short drive and you can visit the capital or the Austin music scene. San Antonio is a really romantic city to be in.