We got married in Yoho and did a wedding day hike to Laughing Falls.
If I had all day, I'd probably start at Emerald Lake, hike along the lake up to Yoho Pass between Wapta and Michael Peaks, then maybe on to the Iceline trail a bit. You'll get awesome views everywhere - Emerald Lake, Takakkaw Falls, peaks, lakes! You could always get to the Iceline Trail from the other side, but this way you get to see Emerald Lake. Reward yourself with a meal and drink at Cilantro on the Patio when you return to Emerald Lake!
(hiking PDF will prompt you to save or open)