It depends on the fog at SFO. If no fog and if the flight is on time it's plenty of time to make the connection. Fog can occur anytime, but more in warmer months (well it used to be) and more midday. If all the flights are delayed, then you'll probably be ok. The risk of another stop (adding the opportunity for delay) for me is about the same as a short connection. OTOH, if you make it to Houston on time, you've got a lot of time to make it to SFO. Houston has thunderstorm problems in summer. You may be able to make a change if you get an amenable agent.

Since you're visiting family, is a day delay that horrible? I think I'd just have a back up plan for a day delay.