My local store (corporate store) has typically let me come in and "play" with the display phones, which I do from time to time just to see what's new.  I too, do a lot of research and comparison shopping before I ever get to the store, so I pretty much know what phones I want to look at, and what features I want to explore.

I haven't been in recently though, (6 months or so?) and things may have changed - I usually am approached but say I'm just looking, getting ideas ... they haven't been overly pushy.