Ribbon Creek to Ribbon Falls (and back) is a little longer, but with a little less elevation gain. Good trail the whole way.
I also recommend the flat-to-rolling 16km Upper Kananaskis Lake Loop.
You can make a good run up to Elbow Lake and beyond to the Tombstone area. The trail goes for days that way, so you can really make it as long or as short as you want. It's a short steep start to the lake, and then broad and rolling.
You might enjoy a run up Buller Creek. Buller Pass is a 14km loop, 650m-ish elevation gain. A chunk of that is right at the end. so if it's a little more than you want, you can certainly get up into the valley and enjoy yourself even if you don't want to go to the pass (though it's worth it).
Lake Minnewanka is not runnable right now due to wildlife concerns, but if you're making a general list for the future, it's great from May to mid-July.
If you want to take the White Mountain Adventures bus to Sunshine Village, you can start running right up in the meadows, and make a day out of a combination of loops. If you don't want to take the bus, it's 18km and 660m of elevation gain to Healy Pass, but good parks-maintained trail the whole way.
The Moose Meadows parking lot is just west of Johnston Canyon, and its trail skips past the canyon to join up above for the route to the Ink Pots. I wouldn't do it in high season, but it's calming down right now and should be in that same range.
Wilcox Pass at the Columbia Icefields would make an awesome run if you want to go make a weekend out of it sometime. Consider Nigel Pass for the other day.
Burstall Pass off the 742 is a longer day (16km), but still under 500m gain, and is a truly awesome place. The trail to the pass is interesting, and the pass itself is the sort of place that makes you want to run around and explore.
is a good book by a guy who knows the area and has great suggestions for now and through possible longer future endeavours. I've seen it sometimes at the Calgary MEC, and definitely at the Banff bookstore.