Hi Matt,
Spiders are suggestive rather than imitative and as such could be taken for emerging insects, drowned insects etc. I would and do fish them without a weighted fly during a hatch in the right place. I will often fish a single spider upstream as you would a dry fly and if fishing a team of them for searching the water I will fish the about 45 degree upstream and dead drift them down as far as possible with a high rod tip then let them swing, until the swing takes are visual and you are watching for them as much as feeling for them. I tie mine of light wire hooks, such as B400's and will use a weighted nymph to take them down if required.
Cheers
Ben