We stayed for four nights in late June. The Doubletree is a class of hotel we normally don't stay at, but lesser chains were nearly as expensive, plus the location, one block from the downtown historic area and the D&SNGRR depot, was a plus. So we took the plunge and paid a little more than normal for the convenience. The experience was positive, overall.
Having stayed at similar class hotels on business, I'd say this Doubletree is a lesser example of the brand. We were on the top ("fourth") floor on the 'city view' side, not wanting to waste $20/day on the view of the Animas River. The road noise from US550 was minimal and the room was quiet overall. The room itself was nicely appointed and fairly roomy. The staff was helpful, but all these benefits aren't worth the normal rate. We paid a discounted advanced purchase rate and took advantage of a $75 off promotion. At this rate the cost was about the same as the 2-2.5 star chains in the area, but there's no doubt you're staying in a resort area where hotel rooms are in high demand.
Due the the close by and numerous external options, we did not utllize the on-site restaurant or (ridiculously expensive) room service. There is a cafe on the river with extremely limited service hours - during weekdays only. Again, with superior options elsewhere we took advantage of them.
The hotel does have an indoor (heated) pool and spa, and there was a sauna in the men's dressing room (but not the women's). We took advantage of the pool, which oddly looks out into usually-closed river cafe, as well as the jacuzzi. There's also a small fitness room on-site with decent equipment. Showers are available in the pool area.
The hotel is also located on the Animas River trail, a paved trail running five miles along the river. Jogging, running, and biking is a simplematter of stepping out of the first floor exit and directly onto the trail. It would be nice if the hotel rented or otherwise made bicycles available.
Good: The entire downtown area is easy walking distance; nice rooms; quiet; very convenient to Durango & Silverton RR; river views available if you're willing to pay for them. Nicely appointed rooms. Tasty warm Doubletree cookies on check-in (and they gave us a couple more our last night there). Friendly front-desk and English-speaking cleaning staff (with names on carts, a nice touch).
Not good: Pricey unless you search out discounts; a smallish Doubletree with somewhat limited options for a hotel of this class.