Good stain and sealer product

[becket]

I am putting Down 1x6 spruce boards (over the sub-floor) for flooring in my new 10'x20 barn type shed; it will only see motorcycles, nothing really heavy. I need to know if I should use Thompson's water sealer first, then stain over; or, if there is a quality sealer and stain one-step product you recommend? Thanks for any help. I will post pics as the interior gets done, kinda budget-style project but I won't skimp on the important things, of course.

edit: should I screw down, nail down, or glue down, the Spruce?