have finally got to the very last chapter

Now I have to make the big decision - do I "go out with a bang" and throw in a couple twists (which could lead to a second book ) which I do have a couple ideas for.... or do I just neatly wrap up the adventure for this one and see what happens for this book?
What are your experiences on ending your first book. Is it better to show that you could have a second book out there or is it better to conclude the one you have already?
Thoughts?
