Yes I try to fly with the same airline or one of their Star Alliance partners. This keeps the points flush and healthy which I use for myself and my daughter.
During 2010 I earned enough points for close to 2 free trips to LOS (75,000 per) however I elected to go for the big biscuit and used 100,000 for a business class ticket last December. It was worth it.
As mentioned earlier, the tickets I purchased in 2010 were reasonable in my opinion. But the ticket quotes for 2011 are remarkably higher in comparison.