Made the very move you are considering in 2000, moved from Fremont CA to The Woodlands. The Woodlands is a flat version of Woodside, Portola Valley, Saratoga. Lots of trees, very good schools, parks, paved trail system, mall, outdoor concert venue (think Concord Pavilion or Shoreline Amphitheater). House prices are about half of what you would pay in NorCal to get about twice as big of house and lot. Close enough to downtown to enjoy the opera, symphony, theaters, restaurants, sports teams but avoiding the traffic. Has a rep for being stuck up and "Stepford-like" which should remind you of how places like Danville and Woodside are often described.
I was president of ROMP so I can tell you, MTBing is going to be less diverse and available. I live minutes from the trail on Flintridge; when I first moved to the Houston area I drove hours to find good trails (eg Bluff Creek Ranch near Warda). Closer by you have Memorial Park, Cypresswoood, the Ant Hills, Double Lake and Huntsville. But most riding in Texas will emphasize singletracks and roots and not long climbs and descents. If you have ever ridden the trail system near Pacific Union College in Napa, you will be able to picture riding near Houston. Just add lots of heat and humidity. And mosquitos.
More people ride road bikes here. But to be honest, riding on the road is more dangerous than in the Bay Area. Fewer good bike lanes, larger vehicles, and less bike awareness here than in California. And as more people move here the traffic gets worse, roads get widened, and the situation gets worse (eg 1488 used to be a great road ride... now you are safer riding on I-45). That said, there are a lot of road bike clubs and a great two-day charity ride between Houston and Austin called the MS-150. And there is a IMBA-affiliated MTB club called GHORBA.
Happy to answer any follow up questions. Hope this helps.