I'm not sure of the mileage but we have done I25 to Springer and then east on US 56 to Marion, KS, east on KS 150 to US 50, US 50 to Emporia, then either I35 or I335/I70 to KC, depending of what part of KC you are headed to. It is good roads all the way and the grades around Santa Fe are not bad at all. We prefer US 56 to US 54 because there is not as much truck traffic and the road is/was in better condition. It is a super two and the slow downs for towns are not bad, actually kind of a nice break. There is a stretch between Springer and Clayton, NM (about 60 miles)with no fuel stops so you have to plan accordingly.