As others have said, the road is fine. I don't recall any issues with the seams/expansion strips being a problem.
Rather than taking US 36 all the way to I-70 outside of Denver, consider taking KS 27 north from US 36 just outside of St. Francis KS. That will take you up to US 34, which you can take all the way west to Estes Park.
HOWEVER...you don't say WHEN you plan to do this. The suggestion above will work only after Memorial Day weekend, for the entire way up to RMNP. US 34 is currently closed for construction in the Big Thompson Canyon west of Loveland and is scheduled to reopen for the Memorial Day weekend. IF you're planning for before Memorial Day, you can still take US 34 all the way to Loveland, then head south on US 287 toward Longmont, and at the north edge of Longmont, take CO 66 west and then take US 36 up to Rocky. With this route you avoid the Denver mess and having to go through Boulder at all.
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