Cooking down tomatoes
I definitely think you should cook it down.  I sometimes use canned whole tomatoes to make sauce by slicing them open and letting the liquid out, and combining that with the liquid from the can and whatever else (e.g, a bit of white wine).

I roast the tomato solids under a broiler with some sweet onion and garlic (starting the onion 5-10 minutes before anything else).  While that's happening I reduce the liquid by half, so it is a bit syrupy.  Exactly how much you boil off I guess depends on your ratio of solids to liquid.   The whole process takes maybe 20 minutes, then I combine the two in a blender.  If it's too thin or too thick, you can always reduce it further or add some water.

Roasting the tomato solids gives the sauce an enhanced flavour.  Credit where it's due: I got this idea from Alton Brown's "Good Eats" -- but I don't recommend the specifics of his recipe, which involve way, way too much vinegar, sugar and capers.  There's no strict recipe needed anyway; just add whatever you  normally would (or wouldn't).  Reducing a liquid and broiling tomatoes is pretty straightforward.