I overnighted at Grace Lake a couple years ago. Nice little campsite, though not spectacular.
The camp is right on the edge of the lake in some very thick trees, and since its all surrounded by mountains it is in the shade pretty early so can feel kind of dark.. because the trees are so thick and there's a lot of down trees the campsites are rather small, seemed like it might be hard to get two tents on any of the campsites... BUT its a very low traffic spot, so its very likely you won't see any other people. There was no one else there the night I was there and didn't see anyone on the trail in or out from Logging Lake; and I saw less than 10 people total on the Logging Lake portion of the trail.
I would say little elevation gain, but not NO gain... There's a bit of a climb right from the trailhead and then it levels off along Logging Lake, although there is a bit of up and down along the lake; and then there's another short climb up from the head of Logging Lake to Grace Lake. I hiked in to Logging Lake, camped there for a night; then hiked on to Grace lake and spent a night there; and then hiked all the way out. I think you're right its 12-13 miles from Grace Lake to the road. Hiking out it wasn't too bad, although a bit of a long day with a full pack; hiking in all the way from the trailhead to Grace lake with a full pack might be more than I'd want to do, there's no serious elevation gain, but there's some.
There aren't any spectacular wide-open views, but you are surrounded by peaks all rising straight up from the lake, so its not like its a bad view.
There is an old abondoned trail north along the lake up towards the pass between Trapper Peak and Vulture peak, I tried to follow it for a bit, but its all over grown with brush.
I didn't see any wildlife other than the loon pairs on the lake, and some swans on Logging Lake; oh and a couple deer walking through the Logging Lake camp.
LOTS of misquito's on Logging Lake, but they didn't seem so bad at Grace Lake.
I didn't do any fishing, but there were quite a few fish jumping on Logging Lake, although they appeared small. I did encounter a ParkService/FishAndWildlife crew on their way in to Grace Lake with some big electric wand thing, and they were going to "stun" some fish in Logging Creek above Grace Lake to count and measure them. They were staying at the patrol cabin at the head of Logging Lake.
The trail was VERY brushy, especially bad along Logging Lake, I hiked many long stretches were I couldn't see my feet or where I was stepping.. Gave me the feeling that the trail crew had come through and only sawed out the big blowdowns blocking the trail but hadn't done any brushing.
The campsites at Logging Lake and Adair are "prettier" but mainly just because the lake shore at those camps are a little more sandy/gravel and a bit more open.
If you're looking for solitude, you'll probably find it here; quiet, probably (except for the loons, but thats a good kind of noise); spectacular views, not so much.
If you go to this web page <
http://mattb.drizzlehosting.com/glacierRoutePlanner.htm > and pick Grace Lake and click the details button, you can see a couple pictures.