Yes, both are good.
34 is Trail Ridge Road and is the highest paved pass in the USA (a little over 12,000 feet). Beautiful road, absolutely spectacular scenery. I rode it fully loaded, it is not horribly steep, but is a very long climb, with somewhat limited services. Expect tourist traffic, but the road is so twisty that the cars go pretty slow, and it is reasonable. You can get severe thunderstorms (with hail) in the afternoons all year round, so try to be up and over the top of the pass by 1 or 2 pm. After you get to Estes Park, there is an awesome side canyon, Devil's Gulch, that is a great alternative to descending 34 all the way to Loveland. It does link back in to 34 after about 8-10 miles. If you go that way, the cinnamon rolls in glen haven are renowned among the local cyclists.
If you are heading south from there, look into taking the Peak to Peak highway (7 to 72) south from Estes Park through Ward down to Boulder, for some really great riding. Or stay on 7 all the way to Lyons for my favorite descent out of the mountains. Or you can just drop into the plains on 34 or 36 out of Estes.
I rode Hwy 14 (Cache de la Poudre) in the other direction, going West to East you will get a shorter steeper climb (sorry, don't know grade, went the other way), topping out a little over 10,000 feet, and then endless gentle downhill, in a pleasant canyon, with limited services and a little too much fishing traffic on weekends in the lower (east) side of the canyon. Very pretty.
On the east side of the rockies, the front range towns are very bike friendly, and have lots of services. Boulder to Fort Collins is road bike heaven.
