Fly into Albuquerque, and drive via Tijeras Canyon (across the Sandia Mountains), through Golden and Madrid, up Highway 14. It takes about 20 minutes longer than going straight up I-25, but you see more scenery.
As you drive, remember that much of New Mexico's rural economy is based on livestock ranching. You'll pass through moutainous terrrain, but note how dry it is -- with drought tolerant trees such as Pinyon Pine and Juniper (a kind of cedar).
Walk, Motorcycle, Car, Bicycle; NO LARGE VEHICLES downtown! Much of what you'll do in town is within a few miles of the downtown plaza -- so bring your walking shoes. In the spring, don't forget a windbreaker and something to keep dirt out of your eyes. The bus station is downtown too and one route takes you up to some of the museums. The views from there are nice. If you have the opportunity, a motorcycle is best, no helmet preferable (more sunshine and scenery). There are no bicycle lanes, and roads are narrow; act like a car (stop at all lights, don't skirt past traffic to get in front at a stop) and people will respect your space. However, there are lots of tourists, gazing around and not watching the road, so don't ever expect a driver to see you -- make eye-contact. Downtown is small and crowded, leave your motorhome in a parking lot on Cerillos, and take a bus (run after 6 am until after 8 most nights) to downtown.
Walking, bicycle or this little tour bus.
Santa Fe Express, open air bus (in cold weather, regular tour bus). Corner of Lincoln and Palace Avenues, at the northwest corner of the downtown plaza. (505) 983-1570. 75 minute tour, $7 for adults/$4 for children.
Hwy 599 is an awesome bypass around Santa Fe if you are heading north...traffic can be a pain, so this is a great time saver. You know what you see in this picture at Rush hour?? no cars