We moved back from Houston in 2012, and my kids were at the British School. They got a good education, though the fees are astronomical, but they get away with it as most expat kids' fees are paid by the company.
DS left at the end of Yr 8, and DD at the end of Yr 6, and they both passed entrance exams to good independent schools back here, and are not behind or lacking in any way, so I can't fault the education they received there.
The school itself is pretty run down but I hear there are plans to relocate to a new purpose-built site in 2015, so that will be great.
The headmaster and his wife run the show (she's head of sixth form) and are interesting characters - but they get the results and it's not a popularity contest.
The school community is great - very welcoming and sociable and it will make your transition very easy if you decide to put your kids there.
Other schools I would consider are Awty and the Village School.
Just to warn you - there is nowhere in Houston doing A-levels now, they all do IB. It's a great qualification but not for everyone.
Feel free to PM if you want to ask me more 