In article om,
wrote:

Problem is, there are some large gaps inbetween some of the planks on
the floors that are refinished. Now I know of the tricks to fill these
using a mixture of sawdust and glue (or varnish) but don't have any
sawdust. What are some other alternatives?

Yes, do nothing! It's winter time and the floors will contract from
the low humidity. If you fill those cracks, you are going to have a
serious problem when the humidity goes up in the summer. As in bulges,
bows and bumps all over the floor.