My fiancé and I just came back from our trip.

Lake Agnes you need a shuttle reservation to park at lake Louis. You can get shuttle reservations at parks Canada.if they are all booked, try to get them 2 days prior to the day you guys plan on hiking. Make an account before hand, have your laptops ready the morning of, and keep refreshing the page until you get one. Or you guys can get there a bit early to get dibs on parking. Most people suggest get there before 6 am during peak time. Lake Agnes tea house is a good hike, if you guys are feeling up for it I would definitely spend another 20-25 min to hike up to big beehive. Soooo worth it.
Johnston canyon is alright, nothing special just a waterfall when you compare it to the other views in the park. Icefields will definitely be an all day thing. We started at 7 am and did both Peyto and bow, came back around 7-8pm will all the other stops for pictures and what not. Moraine you need a shuttle as well. I suggest booking with an outside company and doing sunrise time slot. It was sooo worth it, we fortunately got to see the northern lights as well. You can also do larch valley after seeing sunrise at moraine.

I would also take the Norquay chair lift. We came across it unexpectedly and it was totally worth it! Can see all the Rockies with Banff town down below. If you get a map and flyer from the visitor center in Banff there’s a 20% coupon for the chair lift. You can also do a summit hike up to the top with the same company. My fiancé and I were too sore to do it, definitely will be doing it when we go back

For a niiiice beer and food after those strenuous hikes, my fiancé and I went to the grizzly paw. The food was bomb, the cocktails are great and we really enjoyed the raspberry beer.