Burley built the biggest bang for the buck.
Santana, while a good tandem, has always been over-priced. They also have too much 'unique to Santana' stuff': wider rear dropout spacing, over sized headsets, wheelsets, etc.
Have ridden several thousand miles on Santanas and Burleys so do have some actual real-time riding in.
Just our experience/opinion.
Suggest you ride the Burley and see if you two are compatible. In a year or so, you'll be more tandem savvy and you can always upgrade or get a new tandem.
Pedal on TWOgether into 2010!
Rudy and Kay/zonatandem