I'm planning on starting a tour mid-June, from Bend OR to Madison WI. I'm skipping the coastal mountains because I know I'm not in shape for tackling Santiam Pass--and my brother-in-law died going up that pass 9 years ago from heart failure. Call me superstitious, I don't care.

Anyway, the Adventure Cycling routes go from Bend over to Council Idaho, then up to Missoula, then either north to Great Falls, South to Billings, but ending up in Glendive MT. Then it is across North Dakota and MN, down to LaCrosse WI and then I'm on my own to Madison.

I haven't added up the miles because it is parts of different routes on Adventure Cycling maps, but it seems well over 2k.

Google Maps gives a much more direct route that is about 1900 miles, but goes almost direction east from Bend OR to Boise ID, then the route goes fairly directly across Idaho, Wyoming, Nebraska, and Iowa. It uses Rt 26 in Wyoming, for example, which I've read is a good cycling route.

Any feedback on which choice to make?

My wife and I used Highway 20 from Newport, OR to Boston MA. Highway 20 and 26 share the same road in a number of areas. I suspect that is the route you are looking at. I'm not sure where to head north to hit Madison, but Dubuque, IA seems like a good point with Madison not too far north. Highway 20 is a great route. It is the longest contiguous coast to coast highway in the US. Also there are not many bikers on that route so you are still a novelty, and people are pretty open. Some improvisation is necessary, but we really enjoyed the ride.

I live right in the foothills about 45 miles west of Santiam Pass. Depending on your timing, I'd be glad to ferry you over the pass. We live very close to Highway 20, which is one of the reasons we picked it as a route.

Take a look at our blog site in 2007 to get a feel for the route.
Doug and Donna's LiveStrong Adventures: June 30 - July 2: Sweet Home to Bend

i wouldn't trust google maps at this time. i've seen it route cyclists through remote wilderness on trails. not that that is not doable, but they need to have something that delineates MTB routes and road routes. i would follow ACA, and on occasion, bushwack with a state or county map if necessary.

for instance, on an East/West tour i had reason to stop in Ann Arbor, MI. the ACA route didn't go that way, so someplace in eastern Pennsylvania i struck out on my own to Ann Arbor, using local and state maps. i eventually met back up with the ACA route somewhere in Wisconson or Minnesota. all in all i didn't do too badly on my own, a couple of unanticipated/improptu gravel road excursions and maybe a few miles of backtracking when my optimism got the better part of me, and i ignored a "Road Closed" sign.

Use ridewithgps.com to plan a diy route. I'd take this one, having ridden some of it. OTOH, ACA routes have much to offer.

US 20 is a pretty straight shot - but there are climbs in Idaho and Montana that are steeper than Santiam.
US 26 offers a shorter route across western Wyoming, but with more climbing.

The easiest crossing of the Continental Divide is at Marias Pass on US 2 in Montana - just south of Glacier NP.
There are a combination of roads from Portland, WA 14 thru Pasco and Spokane to Sandpoint that are moderate.
Then after Glacier via US 89 to Great Falls and MT 200 / MT 59 to Miles City and US 12.

Only about 50 miles further on 2000 total.

I've been thinking of doing something along these lines starting on the west coast and ending up back in IA. The ACA maps are great. Haven't thought about doing hwy 20 but if it has a decent shoulder than it will certainly make route planning easier.

While Hwy 20 has areas of good shoulders, there are also areas of where it turns into Freeway, and areas with no shoulders. However, there are usually good alternatives paralleling Hwy 20. I'd estimate only about 60-80% of the miles were actually on the Highway.

Don't discount the convenience factor associated with the ACA maps, especially if you are sort of person who likes to know where he is going to stay and eat every night.

Also, east of Missoula you have only one hard mountain pass--Lost Trail & Chief Joseph Passes (three miles apart). The next two--Big Hole and Badger---are not bad. You will hardly even know you are climbing Big Hole until the last 3 miles.

Twenty years ago, I went from Bend to Lewiston, then up the Lolo Pass to Missoula, and stayed on US Hwy 12 across to Minnesota and Wisconsin.

That is pretty encouraging. By looking really closely at the Adventure Cycling overall map and then using Google Maps to get mileage between towns, I was able to get a pretty good estimate for the ACA route-2226 miles, Redmond OR to Madison WI. The direct route using Route 20 and 26 is 1905 miles. I don't think it is worth an extra 300+ miles to me, just for the convenience of having ACA maps. I'll be carrying camping gear and can camp anywhere.

The bit around Grand Tetons worries me a little, but I'll be in much better shape by the time I get there.

If you go with the Highway 20 route, you will not have to worry about the Grand Tetons. Actually the steepest part of the western portion of the route is Tombstone Pass, just before reaching the Santiam Pass. Both the ACA route and Highway 20 intersect near Yellowstone NP. You will also find out that there is no such thing a "flat".

While I believe ACA is a great organization, and I am a member, I don't necessarily choose their routes. I believe that too much information takes some of the adventure/challenge out of bike touring.

Whatever route you decide upon, have a fun and safe ride!

Doug