Advice needed

End of July DH and I are road tripping with 2.5 year old DS for my sister's wedding. According to google it will be an 18.5 hour trip each way. We will likely do at least one extended stop since I am suree it will take much longer than that with a toddler who can't sit still for 2 minutes much less 20 hours. 

Any advice on when to travel, how often and when to stop, things to keep us sane? One way or the other we may be ok making multiple stops for fun activities. We are still working out the exact dates and how long a trip overall we will make it (interperet as how much time to request off at work.) 

any input would be helpful as we have not done a long car ride with him since he was young enough to sleep for most of the 8-10 hour drive when he was less than a year old.

Thanks!