Good question!

Two lists -- The Obvious Ten (aka the "Duh" list) and The Distinctive Ten (what the better shops would carry)

The Obvious Ten:

1. Fly rods
2. Fly reels
3. Fly lines
4. Backing
5. Leaders
6. Tippet material
7. Flies
8. Boots
9. Waders
10. Vests or packs


The Distinctive Ten:

1. Local maps or books on fly fishing hot spots
2. Locally tied and focused flies
3. Similar lists/maps and flies for adventure travel (e.g., Alaska)
4. Instructional videos or DVDs
5. Full range of tying materials and equipment
6. Hatch charts or similar guides to seasonal fishing
7. Safety gear (sun screen, inflatable vests, wading staffs, buffs, gloves)
8. Fly fishing oriented recreational reading or viewing (books and DVDs)
9. Expert advice dispensed in a non-patronizing way
10. Staff who emanate the enjoyment of fly fishing and are willing to share their knowledge and enthusiasm.

Just my thoughts on the topic. Yours?

1:Drift boat rentals with drop off and pick up.