Save RMNP for another trip. You have plenty to see/do in Southern Utah for 5 days. Where are you renting the car?
My favorite place between SLC and Denver is Glenwood Springs.
GWS has a great bus service to Aspen (41 miles) so you don't need a rental car there.
I love arriving in Glenwood on the California Zephyr (Amtrak).
The station is within walking distance of two old grand hotels and the largest hot spring fed swimming pool in the world.

Flying to/from Denver and renting the car from there. I have some business to attend to so I unfortunately can't spend the entire five days in Southwest Utah.

It's a minimum six-hour drive to Moab from Denver, so unfortunately, a lot of your five days will be on the road. However, it is a very scenic drive on the interstate and early September is usually excellent, weather-wise.

In Moab, you might have time for quick drive along the rim of Canyonlands, which is so worth it, very different from Arches even though they're essentially across the road from one another! Also, the hike to Delicate Arch is well worth it, for the quintessential photo op at the top.

In RMNP, one of my favorites hikes is to The Loch, near the Glacier Gorge trailhead. I'm not sure if road contruction is still requiring drivers to park and take a shuttle into the Bear Lake area, but the rangers at the entrance can give you the lowdown on that.

Anywhere you hike at either end of your trip will be spectacular and you'll just have to plan another trip out here to take in all the spots you'll have to miss this time around!

Oh, I forgot to mention, if you're driving to Moab in the daylight, take the exit from I-70 to Hwy 128 at Cisco. Drive into to Moab this way instead of going to 191 because the scenery is so amazing the closer you get to Moab, sheer rock canyon, vivid colors, quite beautiful!

I would still save RMNP for another trip to Colorado. Still check out Glenwood Springs either on the way to Moab or on the way back. I've read bad things about the cost of rental cars from the Denver airport. The other option is to take the morning train (CA Zephyr) out of Denver to Grand Junction and renting the car there. The scenery is so much better from the train than driving through it on I-70.

If you can get to Arches in the early morning for sunrise, it is really nice!

Keep in mind that a lot of Canyonlands and southern Utah are best explored in a rugged or four-wheel drive vehicle.

In Colorado, on the way to RNP, we like driving the Peak to Peak Scenic Byway, which is very cool.

Thanks for the help everyone, I appreciate it! Wish I would be staying longer, but it just means I'll have to come out here again

Rental car is already paid for, so I'm not worried about cost. And driving doesn't bother me (daughter of an over the road truck driver). Looking forward to hiking and some gorgeous scenery!

Stick with either just CO or just UT. You don't have time for both. 5 days would be just enough to do one or two areas in either state, but I wouldn't attempt to more than 2.

If you are flying into Denver, then driving to Moab, look into going into Grand Junction then renting a car and driving to Moab and back to GJ then flying back to Denver. This might give you more time in the parks.

Not sure how much time you actually plan for Moab. Arches can take a full day especially with a Fiery Furnace tour. Definitely do Devil's Garden, the Windows area and Delicate arch.

If you have more time in the area then in Island in the Sky section of Canyonlands, hike Mesa Arch (Great at sunrise), Aztec Buttes and see the Shafer trail and Green River Overlooks.

Visit Dead Horse Point.

The one hike that I love that isn't in the park is Corona Arch. It is about a 3 mile rt, accessed from the Potash road.

You can also hike around Fisher Towers on hwy 128.
And Negro Bill Canyon

And since I expect you won't even have time for all of that, you don't have enough time for Goblins Valley, Little Wild horse or Horseshoe Canyon which are a significant drive further west (and in the case of Horseshoe canyon a long dirt road and 7 mile hike which could take a full day.)

Of course you could spend all your time in Moab and then you might be able to get it all in... would have to leave RMNP out of your plans though.


Colorado NM just outside Grand Junction has some nice hikes as well... though most of them are longer and would eat up time.

If you have extra time (sounds like you might not) but Escalante in Utah is also beautiful along with Zion NP. So many beautiful hikes and scenery

Given that you barely have enough time to get to Moab and still see anything, don't even consider anything beyond that like Zion, Escalante or Goblins Valley.

I'd agree that you should leave RMNP out as well, even though I love the place. It's just too much driving.

If you want an easily accessible hike with spectacular mountain scenery that is along your I-70 route, then Mayflower Gulch is the best option that I'm aware of:
http://www.summitcountyexplorer.com/HIKES/Mayflower%20Gulch%20Trail%20-%20Hiking%20Trail.htm

It's only 15 minutes off I-70 on a paved road and takes you quickly and easily into a basin surrounded by dramatic 13,000' peaks. It's not quite as good as RMNP, IMHO, but not too shabby and doable for you. Might even see the start of fall color.

Have a great trip.

Hotels and everything are already booked and non-refundable, so unfortunately, I can't spend the whole five days in one place. Had to schedule it around work plans, just figured I would see a few spots while I'm out here.

Driving right to Moab as soon as plane lands in Denver at 10am on Wednesday. Have full day for Arches on Thursday, with fiery furnace. Half day on Friday before making the trip back to Denver. Have all day Saturday in Denver, figured I would either do RMNP or see the Aspen in Vail.

Ideally, not much time to truly get a feel for either place, but since it coincides with other arrangements, I might as well see as much as I possibly can with the time I do have. Seems a waste to not see some of it simply because I can't see everything. Like I said, it just means I'll have to come back again.

Instead of coming back to Denver and THEN to RMNP, go to the Park from the western entrance and at least get a look at the Park. Go to the airport from there.

I agree with Gretchen's advice to enter RMNP from the western entrance on your drive back from Moab, unless you already have your room booked, paid for and non-refundable in Denver on Friday night.

Bear Lake Road is closed to private vehicles between 9am and 4pm every day. They are reporting 2 hour shuttle delays but I think that must be in the afternoons on the weekends. I am in the park now and haven't experienced any major delays, but I have only driven down Bear Lake Road prior to 6am. This morning the parking lots were basically full by 9am, so if you do want to visit that area, arrive as early as possible to make sure you either get a parking spot or don't have a super long wait for a shuttle.

The aspen are already turning in some places, it is very sporadic, some at higher elevations but even some along the lower meadows.

If you only have Saturday for RMNP, I would get up really early and try to be inside the park by 8am at the very latest. Drive to Bear Lake, hike to Nymph/Dream/Emerald Lake from there. Drive to Sprague Lake and walk to the other side of the lake for a classic view of the Continental Divide. Have a little picnic there - pack a cheap disposable cooler for the day (and your days in Utah) as you don't want to waste precious time driving back and forth to town for food. My preferred alternate to Sprague Lake is Bierstadt - you can hike there from Bear Lake and it is mostly downhill after an initial climb. Much quieter than Sprague but would add about 3.5 miles of hiking to your day.

Next, depends on 2 things - weather and where you entered the park. I would highly recommend driving Trail Ridge Road - but not necessary if you entered at the west entrance (Grand Lake) and not much fun if it's raining/snowing. If you do drive Trail Ridge Road, absolutely stop at Rock Cut and do the short hike there. It will take your breath away. Also, the Forest Canyon Overlook is nice. The Ute Trail is also nice, much quieter than Rock Cut but you must watch the weather as you are completely exposed to lightning.

A lower elevation hike with good views is Deer Mountain. There is also absolutely nothing wrong with finding a nice spot to sit around and enjoy the view.

In the late afternoon, find a spot to watch the elk in Moraine Park, Upper Beaver Meadows, Horseshoe Park or along the road just past the intersection of Bear Lake Road and the main park road. There have been decent sized herds gathering and some bugling by the males already.

That should be enough to get you started. If you can arrive on Friday afternoon via the west entrance, you could pack more in on Saturday. Then I might be more inclined to agree with tekwriter and send you to the Loch (and Mills Lake) instead of Nymph/Dream/Emerald.

That's perfect, thank you WhereAreWe