I need to know what hobbies you like before giving you best advice I can.
With that said, here are some suggestion in 30 thoughts style.
- You can spend all your time in Denver and not rent a car, but the best aspects of Colorado are not in Denver. If you want to get the most out of your trip rent a car and get out of the city. Not only that, but the most popular locations will require a car.
- If you're planning in simply Denver, there is a metro lightrail system which goes from the airport to the city and all over the best places you want in Denver. LoDo is my favourite part of Denver, they transformed it from a homeless area into a nice night out with friends or your significant other - ton of restaurants and bars. Another area which I like is north Broadway in the Denver area, it's more hip for young peeps, but there are fun bars and places to also have a good night out.
- The wealthiest area in Denver is Cherry Creek and they have good food places with higher-end clothing. However, one area of Cherry Creek which I absolutely love is Pearl Street. It's sort of high-end as well, but they have some fantastic hidden restaurant and coffee shops (great place for romantic nights). 16th Street Mall (which is just a long outdoor mall) is a cool place, but weed has brought a lot of weird people along that stretch. The Denver Zoo, Art, and Botanic Garden are wicked places, Museum is boring AF. However, if you do like history there are a ton of wild-west tours and museums throughout the state.
- Try to stay away from Colfax Ave - it isn't a dangerous street around in Denver, but you get looneys, homeless, and just that weird feeling.
- Denver is a drinking city, if you like drinking day after day you'll fit right now. It also has an eerie wild-west feel to it, but it's sort of getting lost due to the insane amount of millennials moving from Cali, Wisconsin, Minnesota, and Illinois.
- If you want to see Colorado in its Sunday best, expect driving for more than thirty minutes average.
- Boulder is a chill place to cheque out, I don't really like the place, but if you like coffee and good restaurants with a nice view it is the opposite of a hard drive.
- Go one day into the Mountains to Black Hawk which is one city in Colorado that allows gambling. Personally, gambling doesn't interest me, but to kill an evening that's something you can potentially do.
- I would consider this a tourist trap, but Garden of the Gods is a must for every tourist. It's normally always packed, but it is also beautiful. Its location is in Colorado Springs which is bit more than an hour from Denver. Colorado Springs has some other cool attractions worth the trip like their zoo (called Cheyenne Zoo) which is effin unbelievable and Seven Falls (I have no idea how you get there now since it was bought by The Broadmoor).
- To my friends suggestion above, you can cheque out what's going on at Red Rocks, but honestly it's just a concert hall. If you're not going to a music show or not planning to exercise, I don't see the appeal of the place.
- A town I love is Breckenridge which is around an hour and a half drive from Denver. Hip town, but the sites are rad.
- Glennwood Springs is an absolute must go for me. It is quite touristy, but you got natural hotsprings and the town has so much to do in it from an amusement park on the side of a mountain to underground caves. That trip will be three hours from Denver, but definitely spend a couple of nights there if you do plan on going. Hotel Colorado is a really creepy place, supposedly haunted and you can see why if you head up there.
- Rocky Mountain National Park is also another must go for me and is around 45 minutes from Boulder which is 30 minutes from Denver. Not sure what you'll see there in Winter, but I went hiking in the summer and saw Bear(s) and Elk. Seeing a Moose is what I consider the main prize since a 1,200 lbs animal will just blows you away (not sure how many Meese you get in Calgary). If you do plan on going, stop at Estes Park which has The Stanley Hotel. I mean it's just a hotel with a lot of history, but there is also a cool aspect behind it when you see it on the hill for the first time.
- Keystone is the perfect town in the Winter. Not sure if the lake is frozen as it might be a tad early, but you can play hockey and skate during the winter. They have good slopes for skiing, but again not sure what you like as hobbies. It's a town for everything though. Another place which has skating/hockey on their lake is Evergreen (which is much closer of a distance).
- I quite like Silverthorn and Frisco who have a huge lake, but I have never been there in winter so your guess is as good as mine (might be too cold to do anything).
- The best places to go is a trio of Durango, Telluride/Ouray, and Silverton, but you're looking at a five to six hour trip to the middle of nowhere. They're worth it though.
- Vail is awesome if you want to see a ski resort, but don't want to ski. They have high-end restaurants and wonderful shops to kill time if you have nothing to do (looking at a two hour trip there). Reminds me a lot of a mountain town from Europe.
- I would avoid Aspen, I mean it's not a bad town at all, but the definition of smug. If do want to go to Aspen, research Maroon Bells which is undeniably beautiful.
- A Colorado staple for eating are three places; Buckhorn Exchange (in Denver), Cherry Cricket (in Denver/Cherry Creek), and Beau Jo's (multiple locations). Buckhorn is a steak place since 1890 and have exotic meats, Cricket is a beast of a hamburger place, and Beau Jo's is Colorado-style pizza. If you plan on going to Beau Jo's, notify the server that it is the first time there, I accidentally ordered a 45 dollar pizza once.
- That's all I got as of now, if you do plan on going to the mountains I will notify
@ASmileyFace who can help you further (especially for the fall/winter months). He's our residential mountain man with the beard and missing teeth who's probably raising a pack of wolves as we speak and climbing over a five pound gold nugget.