5-6 days to Tri-cities is about 500 - 600 miles a day (judging from our trips to Montana). That's 10-12 hours of driving, barring road work. I'd factor in a couple extra days for a more leisurely trip.
We would usually make Billings from Soldotna in 4-5 days, running 12-16 hours a day.
Thanks for the heads-up. We're flexible and aren't bound by time, so we may be selling ourselves short at 5-6 days.
