Anyone have a good solution for keeping mice out? What works besides the pellets?

Walk around the outside of your house. Look for gaps where they can get in. Commonly, gaps are left around dryer vents or where pipes enter the house. Stuff the gaps with steel wool. They won't get back in.

If you're using poison pellets, you might want to think again. They'll end up dead somewhere in the house; like inside the walls, and may smell.

Besides the steel wool (which is the #1 thing to do) put a few drops of peppermint oil on cotton balls and leave them where you've seen evidence of mice.
We had a bad infestation for 3 winters in a row and finally got rid em this year by doing those 2 things.

Thank you both, I will try anything at this point! We've had them for several years too and would love it if we could get rid of them once and for all!

Were do you get peppermnt oil?
TIA