What should I pack for Honeymoon to Banff, Canada during the first week of May?

My fiance and I are going to Banff, Canada for our Honeymoon. We are staying for 7 days during the first week of May. What should we pack? How is the weather normally there during May? When does the sun rise/set there?

We will probably do some hiking, spa trips, sightseeing, relaxing, etc. We will be going out to eat some nights at some really nice restaurants.

Thanks for your help!