Greetings Roderick
For accommodation it depends on what your budget or price range is and what type of accommodation you are looking for. In Banff we have everything from hostels to 5-star hotels.
For central hotels there are plenty of options.
The Banff Y Mountain Lodge offers affordable and basic hotel accommodations.
The Mount Royal Hotel is located right on the main street, Banff Avenue, so you would be walking distance to restaurants, shops, bars and nightclubs
The King Edward Hotel is also located on Banff Avenue and has budget-friendly rooms available.
Brewster Mountain Lodge is a great centralized hotel just off Banff Avenue.
Those are just a few of the many hotels available.
You can find more information about accommodations in Banff by visiting www.banfflakelouise.com
The website also has listings and information about restaurants and activities available in the area.
There are also three hostels in Banff:
Samesun Backpackers http://samesun.com/beaverbanff.htm
Banff Alpine Centre with Hostel International hihostels.ca/westerncanada/332/HI-Banff_Alpi…
Banff Y Mountain Lodge http://www.ymountainlodge.com/
Getting around Banff town without a vehicle is definitely possible. Travelling to other locations such as Lake Louise or along the Icefields Parkway without a vehicle is also possible but it requires a bit more organization. That means joining tours with organizations such as Discover Banff Tours.
http://www.banfftours.com/
They have tours of the Banff area, Lake Louise and to the Columbia Icefield.
Explore Rockies also offers tours and transportation in Banff National Park and to Jasper.
http://www.explorerockies.com/
Sun Dog Tours also offers tours and transportation in the Rockies.
http://www.sundogtours.com/
Banff Sedan can arrange transportation and tours as well.
http://www.banffsedan.com/
Banff Adventures Unlimited can also assist you with planning activities in the area.
http://www.banffadventures.com/
For transporation there are also Greyhound buses which travel between Banff and Lake Louise but not along the Icefields Parkway to Jasper.
As for must sees that depends on what is of interest to you and the rest of the group. The Banff Gondola is a fantastic way to get views of the area. There is also the Banff Upper Hot Springs where you can relax in the mineral water and enjoy great views. Horseback riding may be operating in the Banff town area at that time depending on conditions. You can go canoeing on the Bow River or a boat cruise on Lake Minnewanka.
If you are looking for some adventure you could try going caving with Canmore Cave Tours. http://www.canmorecavetours.com/
For nightlife there are many bars and pubs and three nightclubs. There are many bars where you can enjoy live music.
Depending on what activities are of interest to you, I think that four days is the minimum amount of time to spend in Banff and Lake Louise. That would give you two days in Banff, a day at Lake Louise and a day to travel along the Icefields Parkway. However, you will want more time if you are interested in hiking or exploring the area further.
BanffLakeLouise