Exit from I-25 at the Prospect Rd. exit and go West. The interstate can be congested and stressful. If so, you can exit I-25 on most of the exits North of Denver then go West to U.S. 287. Go North. This road becomes College Blvd. in Fort Collins which is near our house.
The Denver airport is your best option (DEN).
It's time to start your adventures
DRIVING FROM THE SOUTH
Avoid Denver in the mid to late afternoon if you can. If you will be coming up from Colorado Springs you should consider using E-470 to loop around the East side of Denver. It is a toll road (plate recognition – you’ll get a bill in the mail). It isn’t inexpensive but it can be worth it.
DRIVING FROM THE NORTH
Nothing tricky here. Find your way to Cheyenne, Wyoming and get on I-25 heading South.
RENTAL CARS IN FT. COLLINS
Hertz, Enterprise, & Budget all rent cars in Ft. Collins. Their office hours are limited (daytime, closed on Sunday typically). Check with them on their hours.
Good bus system. Uber & Lyft. Public bicycle rental options around town.
if you are flying into denver
The Denver airport is big and beautiful. It’s also slow to get through. If you are renting a car figure that it will take at least an hour from when you get off of the plane to being on the road.
If you have somebody picking you up
I recommend that you plan to meet on the Departures deck, West side of the airport. This is one level above the main airport lobby where all of the security screening is located.