Note on San Antonio--its been HOT here the last few weeks, much so for this early in the summer. When visiting outside, plan to stay hydrated.
We have not had a whole lot of rain this year yet, so bugs shouldn't be too bad, especially in the city.
For the Riverwalk--I highly recommend a restuarant called Iron Cactus. Its my fave down there and they have great tableside guacamole. I take visitors there and they are always impressed, especially when they find out mayonaise is not an ingredient in authentic guac.
Enjoy!!
ETA:
DPhiE is celebrating its convention this summer in the DC area.