I've driven through Andorra. There can be very long lines when leaving for customs, several hours long on summer weekends. IIRC entering France was worse than Spain, but there are lines for both. IMO it's a nice but not spectacular drive. Andorra towns are basically tacky shopping centers and can have traffic jams as people hunt for parking places along the main street. I've never been tempted to stay overnight or even stop for a real meal. It's the sort of place/experience where one goes once, but has no desire to return. I've spent more time in line for customs inspection than elsewhere in the country.