I drive a 33' motor home over Santiam Pass many times each winter on my way to Bachelor to ski. The idea that you need an AWD or 4WD vehicle to conquer the pass is silly. I have driven front drive vehicles and for the most part they perform about as well as SUV's without all the weight disadvantages. Small AWD cars are a very good choice and if reasonable to rent would be a fine option. They are not necessary, however. Good snow tires if available on the rental are advisable, and chains are necessary, so ask for them.
The idea of driving down Hwys 26 and 97 to make the trip faster seems like something out of a crack pipe. These highways are generally two-lane highway and bollixed with traffic. Hwy 26 to Government Camp is a terrible and busy drive. It is as likely to move at 40 mph as it is to move at 55 mph as is highway 97. I-5 is a three-lane freeway and while it has heavy traffic it nearly always moves at between 65 and 75 mph. The pass areas on Santiam are closer together and require less time in the high elevation. The passes over Government Camp are farther apart and require more time at high pass elevation. I have driven over both passes for the past 32 years and except for specific weather reasons I always choose Santiam.
Ultimately the best course of action is to determine the weather at Government Camp and Santiam pass and make a choice based on actual weather conditions. Tripcheck will provide the weather/road condition data and cams http://18.104.22.168/Pages/RCmap.asp...RoadConditions
. Government Camp and Blue Box passes are in the NW section and Santiam is in the C section. Click around and figger it out it aint rocket science.