There are so many options, it's hard to know how to choose. Mainly, are you looking to minimize time over the mountains, or spend as much time in them as possible? Do you like riding up and down passes, or are you trying to keep it flatter? Is there a certain date you need to be in Boulder?
There are 2 potential flood zones. Glenwood Canyon bike path is closed now for flooding. ANd the bike path between Copper Mountain and Frisco has an avalanch, can be walked across (scary, due to possible additional avalanches!!). I just talked to a guy at a bike shop in Frisco who told me that - I would recommend as you get closer, call bike shops in Vail or Frisco to see what's going on there. You may need to bypass that section as well, which is a bummer b/c that means you have to do the whole trip either south or north of I-70, where it would be nicer to cross right there around Vail.
Here's some flood info - I was just looking this stuff up this morning, b/c the Glenwood closure is likely going to affect Bike Tour of Colorado, which I am doing.
Vail Pass itself may be ok and may not - it had a TON of snow on the path 2 weeks ago, as I drove by there in a blizzard, but that may be gone now. And depending on how long you linger in the Moab/southwest corner of CO, the flood & snow issue might resolve - sounds like it may peak this week then start going down.
very direct, but not that awesome - Hwy 285 is not a great road, carries too much traffic as you get near Denver, and it's rather open & windy:
(this has the details of how to get from Golden to Boulder I won't do that in the next maps, but use these roads if you can, Hwy 93 between Golden & BOulder sucks)
a bit more convoluted, and nicer approach, more hills. don't be tempted to ride down Hwy 119 into boulder unless you are very confident with riding on a narrow steep, busy mountain road with bad pavement and lots of traffic. Continuing on to Lefthand Canyon (Ward) gives you another 1500 feet of climbing, but it's a fantastic ride, a Boulder classic - and no traffic. Still very steep descent.
tons of mountains, this would be the one i would use if i had unlimited time.
note this shows using Cottonwood Pass from Gunnison to Buena Vista, part of this road is dirt (ascending, the descent is paved), and it is very very high - 12K' - if the weather is bad, don't go this way, but it's absolutely spectacular.
Also, this looks like you are on Hwy 70 after Loveland Pass, but you are really on a new bike path to Bakersville, then frontage roads all the way to Hwy 40.
If the bike paths around Vail and Frisco are open when you get closer, reroute like this:
Basically, your best bet is to stay in the green parts of the map, the white/yellow parts are lower and therefore hotter. Also stay off the "front range" - east side of the mountains - as long as possible, because that's where all the cars & people are. the area around I-70 is most highly populated, as is I-25, and thou you can ride US 285, I-50 and I-40, those have more traffic and are not as safe or nice.
If this stuff doesn't look good, or you have questions, post back here, if you have a phone, Skype or instant messenger, I am PMing you my contact info.