Flash lighting balanced with background

Just a quick question here. I seem to have a problem in which I love the background lighting in churches while at the same time I love controlled lighting from flash for the subjects.

This is mostly related to wedding photography, and while I set the shutter for backgrounds and leave the f-stop for DOF, I constantly catch myself getting motion blur at 1/4 second exposure.

I suppose I could bump the ISO up to get that shutter speed shorter, but I like fine details also.

I'm wondering what other users do to keep this problem from occurring?

Use the ISO you need.
Don't worry too much about noise that won't show up in print...

Using a higher ISO will keep the shots from looking "flashy".