It really all depends on what you are looking for. Yes you could cook your strawberries and thicken them up. You will end up with a nice thick sauce, but then you sacrifice the nice fresh flavor of strawberries in season. Without cooking, your sauce will be much thinner and more runny, but will taste fresh and vibrant. My choice, any day, especially in strawberry season would be to not cook it. Another option would be to top your cheesecake with whole strawberries. To do this, slice off the stem end so that the strawberries lie flat. Arrange them, in concentric circles, so that they cover the whole cake. Then heat some preserves, with a little water, to melt (Apricot preserves work best). Strain to remove any pulp. Brush this over your strawberries to give them a nice shine. This isn't really a sauce, but it looks nice and helps you to avoid cooking your strawberries. As you can see, if you have nice strawberries I really am against cooking them. They just lose so much of that fresh flavor that screams summer. Of course, if you can't get really nice fresh strawberries then go ahead and make a cooked sauce.