That "long stretch" could easily contain the following things that a lot of people in the US keep insisting aren't worth seeing in the "flyover zone:"

Mount Rushmore, Devil's Tower, Grand Tetons, Yellowstone, Glacier Park, Columbia River Gorge, Snake River, just to name a very few.

In March? There is no way I would drive it then unless I were constantly tuned into the Weather Channel. Some roads into places like Yellowstone aren't even open yet.

To get historical data for cities along whatever route you choose (I would opt for I-94), go to www.weatherbase.com. We used to drive from Seattle to Oshkosh every year....but in the summer.

Beginning or end of March? It can make a big difference. Also, what sort of time constraints are you facing?

If you choose a northern route (I-90 is my preferred route for transcons) then you should be prepared for some delays or go-slows due to weather, particularly in the Midwest, Great Plains, and western Montana. If you choose a southerly route, of which I-10 is the most likely to be snow-free, then you're adding at least a day of travel time, maybe 1 1/2 days, accounting for the big right turn you'd make in California. Of course that extra driving time means more fuel, more hotel nights, etc., but it might also end up comparable in terms of total elapsed time if you'd otherwise get stuck in some motel in Missoula waiting for Lookout Pass to open, or someplace else where the roads might be closed. (One thing to look out for is that even southern-looking routes can cross some very high country, e.g. I-40 near Flagstaff, which is occasionally closed due to heavy snows.)

www.viamichelin.com assumes that you would take the northern route in March. I think that using I10 would add more than a day. It's a 12+ hour drive just from San Francisco to Seattle (90 min. less from Sacramento on I5).

www.viamichelin.com assumes that you would take the northern route in March. I think that using I10 would add more than a day. It's a 12+ hour drive just from San Francisco to Seattle (90 min. less from Sacramento on I5).

Google says it would take around 16 more hours wheels turning compared to I-90. http://goo.gl/maps/lQjkd vs. http://goo.gl/maps/NcnqN

If it was me I'd take the northern route too, but it depends on how risk-averse the OP is in terms of time or snowy conditions. Heck, even this week the Grapevine (I-5 just outside of LA) was closed briefly because of snow, and the Siskiyous leading into Oregon can be snowy then too. But the odds of bad weather are lower on the west coast than traveling over both the Rockies and the Cascades in winter, and delays and slow-downs could eat up the time differential. Just sayin'.

Thanks for all your replies. We're aiming at leaving the 4th or 5th of March. We're driving home with 2 dogs, not sightseeing. One anticipated stop is Ann Arbor, where there's family. Other than that, we're open to the best route to get home.

We're on a tight budget and tight-ish on time. ViaMichellin showed 'economic' routes that took 60 hours vs. 43 hrs and I can't see how something that would require an additional 1 or 2 hotel stays could be cheaper ?!? Plus we need hotels that take dogs without paying an extra fee or deposit.

I'd read another Fodor Forum thread that said the northern routes are more equipped to handle snow when it hits, so although I'd love I-10, we need the most direct way there with the least stops.

If we did Minneapolis straight through to Spokane and Seattle (I-90) what cities would folks recommend staying in (dog friendly & vegetarian)? Thx

If we did Minneapolis straight through to Spokane and Seattle (I-90) what cities would folks recommend staying in (dog friendly & vegetarian)? Thx

Rapid City SD and either Bozeman or Missoula MT, depending on what kind of time you can make. Both Bozeman and Missoula are college towns, so more chances of things that will work for you in diet terms. I would take I-90 over I-94; it's both more scenic and might have marginally better weather. Either way I'd pack some emergency supplies - blankets, tire chains, etc. You may be in a hurry, but pushing it, especially in rotten weather or when you're tired, is a bad idea.

http://www.dogfriendly.com/
http://www.petswelcome.com/

If you want to consider a more southerly route, I would check I-80 to I-84 to get into Washington. This adds 2 to 3 hours to the more direct route but might be a bit safer.
From Ann Arbor nights in a motel would be Des Moines IA, Cheyenne, WY and Boise ID. In good conditions the legs between these cities are 9 to 11 hours.