Vancouver, BC to Las Vegas. Which route?

I am towing my 40 foot, tri-axle, trailer with my Chevy diesel 4X4 from Vancouver BC to Las Vegas, and then down to Phoenix.
The trailer weighs approx. 15,000lbs. and I'm worried about steep mountain passes with poor road conditions. I have purchaced new winter tires, and tire chains, but with the trailer wheighing almost 3 times as much as my truck I want to avoid big mountain passes with windey corners.
Mapquest shows a route:
I-405 S toward BELLEVUE, then I-90 E via EXIT 11 toward SPOKANE, I-82 E via EXIT 110 toward YAKIMA, I-84 E via toward PENDLETON.
That would take me through Boise, then Salt Lake. and should take less than 25hrs.

If anyone knows any alternate routes that would be safer and easier for this trip please let me know. Also if anyone knows of good tourist spots or RV Parks feel free to leave a message. Tahnks

It's a nice drive. The few passes you will cross have fairly gradual inclines, for the most part. I've driven this route several times and the only places that might be a challenge are:
* Snoqualmie Pass (I-90 east of Bellevue) - but this is a fairly easy pass and truckers with semis use this route all the time. I don't think it will pose a problem but, if you prefer to avoid it, you could drive down I-5 to Portland and then hook up with I-84 from there.
* Right before the Idaho border....if I'm remembering right...there is a windy, fairly steep hill with switchbacks. At the top is a scenic viewpoint parking lot and I recall several RVs, semi-trucks, and trucks towing 5th wheels and trailers taking a bit of a rest break there before continuing up (or down as the case may be). I would imagine this will be a bit hairy in your vehicle but it's fairly short. I don't believe it can be more than just 3-5 miles. Since so many other RVs travel it, it should be fine for you but I imagine you might have some white-knuckles by the time you top it!

Your only other option is to go down I-5, and then east at Bakersfield, CA. But there are still passes to go over on that route. Especially in southern OR and northern CA. I don't think it's any easier than the SLC route.

I think I'll take your advice and go down the SLC route, I guess there will allways be mountain passes to go over, and it is reassuring to know that is a route that a lot of truckers take. I'll just keep an eye on the road report for snow and ice and all should be good I guess.

Thanks

Do it before you leave and every night/morning before you head out. This post has some general winter-driving tips you should be aware of, and be sure to click on the link to Uncle Bob's winter driving tips for even more good info.

Watching the weather and adjusting your route accordingly is a key to having a good, safe trip.