@Frank Basile, I love where your head is at! Everything you mentioned in your post is definitely possible with the amount of cash you have available for downpayment for HH. Everything my good friend @Jeff White is spot on regarding the the income vs. comfortably scale. Rent by the room being the most profitable but least amount of privacy vs. SFH with separate income sweet (walk up/walk out basement, mother-in-law suite, ADU) being little less profitable but plenty of privacy if you have a family.
To answer your question regarding location- Since you are looking for easy access to mountains and a SFH with potential ADU, I would focus in Wheat Ridge and Arvada (just NW of Denver proper). Short drive to I-70 that will take you up to the mountains in +/- 60 minutes. Now if you are driving on a Friday afternoon, expect that time to be much longer :)
While Living There: While living there as a house hack, you will get the most bang for your buck renting out that ADU/ MIL through websites such as Airbnb and VRBO. Much higher income potential than if you were to go the LTR (>12 month lease) route. STR do require some more time to manage operationally, but with a few proactive systems set up on the front end (bnb friendly cleaner, automated messaging, multiple sets of turnover supplies so you are not stuck doing laundry during the busy workweek) will make life much more easier! If purchasing in area that has a HOA, be sure you read through the bylaws or talk with someone on board to be sure they allow STR's (rentals < 30 days). Even those city laws may allow STR's, the HOA may very well not.
After Moving Out: Real Estate is a long term investment, so when I am analyzing my next HH, I am more concerned what the numbers look like after I move out (investment property) and turn the property into a stabilized rental than when I am living there (primary residence). I will only be HH'ing the property for 1-2 years but it will be a stabilized rental property for 5-10 years. It is always nice to have the option to continue operating that ADU as an STR so that is the great thing about Wheat Ridge and Arvada having very friendly STR (rentals < 30 days) laws for "investment properties". For example, if buying in Denver proper, that county does not allow any rentals under 30 days if the property is non owner occupied.
However, like I mentioned above STR's can me much more work so, while it is nice to have that option to continue renting out bnb as STR, I typically turn that furnished BNB into a MTR (1-6 months) for traveling nurses and young professionals. They make great tenants, income is still favorable, and less work w/ few turnovers. The area of the SFH I was living in while it was a HH gets turned into a LTR. So it is almost like operating a duplex in the skin of a SFH.
Last thing- CHECK OUT THE BANK OF AMERICA GRANT PROGRAM!!! $10,000 towards down payment, $7,500 towards closing costs. No PMI!!!!. Must make below $150,000/year to qualify. Can not be for investment property. And property must be located in a low to moderate income areas. I was very surprised when I put my first HH in Arvada into the map to see that it would have qualified b/c it is in a very nice family friendly area! Program is expected to go until 2025.
Hope this helps!