The ultimate thing for me is price, when i go to the large independant GC's around here i think they are ripping people off.
The small nursery types are charging £1.50 for tray of bedding plants, b&q charge £3-7, but the inde's charge £6-10, the plants are no better. The only redeeming feature for the large ones is the choice.
Here again its difficult to find anything reasonably priced though, an example being a clemetis, the GC had a vast selection, but wanted £15 per plant. This to me is too much for what is a relatively small plant which is at least double, more likely triple to what you can get them for elsewhere.
Is it better quality? maybe, but not by much.
As to coffee shops and all the tat they sell, i am not going to a GC for a day out, but then i expect most of the clientel (older generations) are going for a day out.
That is my early thirties view, which probably is not your customer target age.