Saddle Mountain is a moderate difficulty hike with a seriously high gorgeousness-to-effort ratio. It's a bit over 5 mi roundtrip (out and back), with 1630 ft of elevation gain according to the trailhead map sign. You can go up in about 1.5 hrs and back down in 1 hr, so it's a good hike if you don't have a lot of time but want to still get a solid workout. Allot more time than that, though, for all the stopping to check out the views you'll be doing! Driving time from Portland is about 1.5 hrs.
The restroom was closed when I was there. Maybe not open for the season yet? Not sure. But there was a port-a-potty instead. Also be sure to bring your own water, as I didn't see any water facilities at the trailhead (and there are definitely none on the trail). I arrived around 4p in the afternoon and there were maybe a couple dozen cars in the lot? I was one of the last few hikers up the mountain that day; it had cleared out quite a bit by the time I returned to my car, save for a couple small groups camping in the designated spots by the trailhead. Be patient on the 7 mi drive to the trailhead from US 26 -- it's paved but narrow and there were serious potholes.
As you can see in the trailhead map, you're going to be doing a lot of switchbacks. So don't be surprised when you encounter the 1 mi marker and are like "how has it only been one mile?!". Don't get discouraged, though, as the second half of the ascent has pretty consistently gorgeous southside views to keep your tired quads company, giving way to full 360-degree views as you approach the top.
It's worth noting that the weather on this mountain seems to change pretty quickly, especially the higher up you go. I put on and took off and put on again my hoodie a few times during the hike. You'll see the reason for this when you're at the summit -- big fluffy clouds rolling in fast from the Pacific will sometimes come right over the mountain or sometimes will get pushed to the south instead. (At least that's what I saw while I was eating my dinner up there!)
There is a little bench at the summit with plenty of room to flop person, bag, and food onto, and to have a nice mountaintop snack. I'm guessing it can maybe get pretty busy in the middle of the day, but there was only one other person up there while I was there, so I was able to enjoy clear 360-degree views while I ate! It was quite lovely and peaceful. Supposedly you can see all the way from the Pacific (which is somewhat close) to Hood on a good day, but I wasn't able to see Mt. Hood. I was able to see the Pacific, and all the way to Sisters, I think? I also want to know what that ridgeline off to the south was. I guess that's the problem with hiking one mountain--you see all the others you want to hike next!
I didn't quite wait around for sunset at the summit as I wanted to make it most of the way back down without having to use my headlamp. There's some tricky (but I wouldn't call it very dangerous) footing in the top third (ish) of the trail, and I wanted to be past that before my visibility was limited. (Due to this tricky footing, I wouldn't recommend this trail for dogs--there are a lot of portions near the top covered in wire grating that would be easy for a dog's paw to get caught in.) I enjoyed some real lovely golden rays on my descent, however.
All in all, this is a can't-miss hike for us Portlanders. I absolutely plan on doing this hike a second time before the summer's over.
How to get there:
http://www.oregonhikers.org/field_guide/Saddle_Mountain_Trailhead