Pipes generally won't freeze until it is in the low 20s at the highest. Whenever I have had pipes burst it has been below 10 for at least 24 hours (3 times for those counting).

There are no nights below 20 in the 10 day forecast and all days are above freezing.

I would set it as low as you are comfortable with (45-55) but set the fan to always run - this will help with air settling in an area potentially being colder.

I usually set vacant homes at 58-62 when they are vacant. (Contractor that is a landlord and occasional fix and flip guy - I always have at least 1 vacant house.)