I recommend that the best route for a first time long-distance bicycle tourist is Adventure Cycling's 'Western Express' route. Not because it's easiest, but because the ACA maps (buy them at adventurecycling.org) contain a lot of valuable information regarding where to camp, find water, food, etc. They are invaluable. Get them! There are other routes (and I've taken them), however, by traveling the Western Express route you will come across other cyclists in each direction who can also offer support in various ways. There are places across Nevada and Utah where there isn't food or water for more than 80 miles. So, be prepared. And I haven't mentioned the weather in these desert regions. Do your homework and you'll have an incredible trip. Get the maps!

I don't know what you mean when you say your friend will be riding his "cruiser", but it is no small task to climb over the Sierra Mountains, bike across Nevada's desert and 13 passes, cross Utah's desert and 14% grades, not to mention Colorado's mountain passes. I hope your Giant and your friend's "cruiser" have some serious gears and that you are prepared for such a trip mentally and physically. Don't take such a trip lightly. This is one of the most challenging (and rewarding) routes in the U.S. Continue to research and prepare yourselves and your bikes. If you do, it will be an amazing journey.

Safe travels,